Eating Matzah only by the beginning of the meal:
The authentic Chabad custom to eat Matzoh during the other courses of the meal: Even those who are very meticulous to not eat Gebrochts during Pesach, as is the traditional Chabad custom, nonetheless may eat Matzah during the meal while eating other foods. This applies even according to Chabad custom. So was the custom of the Rebbe Rashab and Rebbe, who would eat Matzah while eating the soup. The Rebbe Rashab would clean his spoon after each time he removed it from his mouth to wipe off any leftover Matzah crumbs, although this was his personal custom and was not a directive to the public. There never was a custom in Chabad to negate eating Matzah during the other courses, and it was simply not eaten together.
The Halachic issue with segregating Matzah eating from the remainder of the meal: In addition to the above clarification of the authentic Chabad custom in the above matter, furthermore, in order to avoid entering a Halachic debate of whether a new before blessing must be recited over the remainder of the meal foods, one is to be particular to eat Matzah during the other courses, in order for the blessing of Hamotzi said on the Matzah to exempt the other courses of foods from their blessing according to all opinions. For this matter, it suffices to simply eat more Matzah prior to reciting Birchas Hamazon, and it is not necessary to constantly eat Matzah during the other courses, or have Matzah on the actual table. Nonetheless, those who are lenient to allow eating meal foods without a blessing even after removing the Matzah from the table have upon whom to rely, and they do not need to be protested.
The practical custom today in many homes, especially with young children: Despite the above traditional and halachic clarifications, some today are accustomed during Pesach, after the saying of Hamotzi to first eat only Matzah, and then clear/change the tablecloth from the Matzah crumbs, and only then bring the other foods which is eaten without Matzah until the remainder of the meal. This is especially accustomed to be done in homes with small children, in which it is virtually impossible to guard the Matzah from contacting foods and liquids if it were eaten when other foods are on the table. Nonetheless, as explained above, one should not be particular against eating Matzah afterwards, during the course of the other foods, as this causes those foods to lose their exemption with the blessing of Hamotzi, according to some opinions, and therefore require a new blessing to be said over them. Thus, one is to periodically get up and eat Matzah during the other courses of foods, even if the table was cleared and one no longer brings Matzah to the table. For this matter, it suffices to simply eat more Matzah prior to reciting Birchas Hamazon, and it is not necessary to constantly eat Matzah during the other courses or have Matzah on the actual table.
 So is evident from Sefer Haminhagim ibid
 Heard from Rav Eli Landau regarding the Rebbe Rashab and Rav Y.Y. Ofen regarding the Rebbe
 Heard from Rav Eli Landau Shlita
 Some Poskim rule that in order for the blessing of Hamotzi to cover the meal foods, and deem the meal foods as secondary to the bread, one has to leave the option open for him to continue to eat bread throughout the other courses of the meal. If, however, one decides (whether verbally or in his heart ) to no longer eat anymore [bread ] prior to one of the meal courses being served [or has no more bread to eat and does not expect to get more], then the remaining foods of the meal are not exempt with the Hamotzi blessing said over the bread, and one must thus recite a before and after blessing before and after eating these meal foods, prior to reciting Birchas Hamazon. [See 1st and Stam opinion in Admur 177:6; Ideal ruling of Luach Birchas Hanehnin 5:12; Tur 177 regarding Seudos Gedolos; Levush 177:2, brought in M”A 177:7; P”M 200 A”A 3; 1st Opinion brought in Biur Halacha 177:2 “Sheiyn”; Chazon Ish 27:3 that this applies even according to the opinion of the Rashba and others brought in Biur Halacha 177:2; M”A 208:24 regarding one who expressed his desire to recite Birchas Hamazon; Based on the following sources who rule this way regarding the Talmudic custom to serve appetizers at the end of the meal, after removing the bread table: Tosafos Brachos 41b; Rosh Brachos 6:26; Brachos 41b]
Other opinions: Some Poskim rule that all of the meal foods are included and exempt with the blessing of Hamotzi said over bread even if one has no intent to eat anymore bread during those courses of food, and even if he expressed his desire to recite Birchas Hamazon, so long as one is eating those foods in the same table that the bread was eaten. [Limud Zechus opinion recorded in Admur 177:7 in defense of custom; Stam and only opinion recorded in Admur 174:9 in parentheses; Opinion recorded in Luach Birchas Hanehnin 5:12 regarding reliance of custom; M”A 177:7 based on Rabbeinu Yonah ibid; 2nd Opinion brought in Biur Halacha 177:2 “Sheiyn” and that so is opinion of Rashba being that meal foods are the main stable of the meal and are hence always exempt even when eaten after the meal; See Chazon Ish 27:2; Cheshev Haeifod 3:10] Some Poskim rule that the meal foods are exempt the original blessing over the bread even when eaten on another table. [Piskeiy Teshuvos 177:9 and 444:13 based on Biur Halacha ibid in name of Rashba]
 Conclusion of Admur in Seder Birchas Hanehnin 5:3 “It is good to suspect for their words and not return and eat at all” [as explained in reason]; Implication of Admur 177:67 and Luach ibid; So rules: Minchas Yitzchak 6:48; Piskeiy Teshuvos 444:13 rules that this is a requirement [unlike his ruling in 177:9 where he defends the custom]
 How much bread must one eat? Some opinions rule that one must eat a Kezayis of bread again. [Minchas Yitzchak 6:48; Piskeiy Teshuvos 444:13] However, based on Admur 184:1 it suffices for him to eat there even a little more bread, even less than a Kezayis.
Must everyone eat more bread? Initially, everyone is to eat more bread. However, some write that it suffices even if only the leader of the home needs more bread. [Nitei Gavriel 19 footnote 8, based on Kaf Hachaim 177:14, brought in Piskeiy Teshuvos 444:13]
 Minchas Yitzchak 6:48; Piskeiy Teshuvos 177:9 and 444:13
 Luach Birchas Hanehnin 5:12 “they have upon whom to rely”; Admur 177:7 “there is an opinion who learned merit upon them”; 1st M”A 177:7; Biur Halacha 177:2 “Sheiyn”; Levush ibid and Bach 177 that so is the custom; Cheshev Haeifod 3:10; Kinyan Torah 3:55