3,639. Three Connected Doughs

Hilchos Bikkurim 7:5

Imagine three doughs: the two on either side are too small to require that challah be taken from them and the one in the middle is a kind of dough to which challah doesn’t apply, such as a rice dough, a terumah dough, a terumah/secular mixture, and a non-Jew’s dough. In such a case, the doughs don’t combine. Even though the two outer doughs are connected, an exempt substance is in between them.

Hilchos Bikkurim 7:6

However, if the two outer doughs are separated by a dough from which challah was already taken, then the outer doughs combine. This is because the dough between them was obligated in challah. Similarly, if a consecrated dough separated the outer loaves, they combine because that consecrated dough can be redeemed and, if that happens, it will be obligated in challah. Similarly, if a dough of a different type of grain, a dough belonging to someone else, or a dough from a different year separates the two outer doughs, the outer doughs combine to require that challah be taken.