That was a good idea. I do that now & then, & it's the same with mice also- if one mom is overwhelmed & another can take a few more.
But with mice, it's best to roll the babies about to be fostered in some used litter from the nest they're going to, as babies can be attacked (killed) for smelling like a different male. Rats are usually better about this, more accepting, but either way, the males use their urine to scent mark, & it's noticeable on the offspring.