A certain bakery in Israel, produces a special challa, made up of a number of individual round rolls put together. Each of these rolls is a sub unit of the larger unit. Each sub unit is distinctive, in that it might have different dough to another ( whole wheat or white), whilst some are covered in sesame seed, others in poppy seed. Can this unit be considered as one challa for purposes of motzei on Shabbat when put with another challa (for lechem mishne), and can I after saying the bracha, break the unit, and give each person present an individual sub unit for their motzei which I have just yotzseed them? Is there any problem if the subunuit are only loosely connected, and in fact may not be connected at all at somepoint?

Shalom, The custom to bake several rolls together into one large challah probably comes from the custom of the Ari HaKadosh who would make ha'motzi on 12 loaves of bread - six on his right and six to his left, or six on top of six. This was in relation to the twelve loaves in the Temple. It could be that even though this custom uses 12 small separate individual loaves, the loaves you have seen are designed based (partly) on this custom. In answer to your question - if two loaves accidentally joined together whilst baking, they are still considered as two separate loaves, and may be used, even if still joined, for the mitzvah of "lechem mishne". There are those who require pulling them apart before using them, and this is the advisable course to follow. In such a case, the fact that when dividing them the place of the tear is left visible does not disqualify them for the mitzvah (even if the tear was not exactly equal and a small part of one loaf ended up stuck to the other, it is still acceptable). If though the loaves were baked with the intent to be joined together - as in your case - then they are considered jointly as one loaf. As such, if you have two such challot, or even one together with another "normal" challah, you are fine for the mitzvah of having two loaves. (If someone were to separate them and then consider them as individual rolls, to use two of them for "lechem mishne" they would have opinions on which to rely). If the sub units are not fully connected, but only loosely connected, it is still considered as one loaf. There is no problem whatsoever in giving out individual small sub-loaves to those around the table after you make hamotzi. (reference - Piskay Tshuvot Shabbat volume 2, 274,9) Blessings.