Huhu,
I hope I understand the question right.
So the nest is fully an urine, or have I misunderstood this (acts to me suffer I come from Germany ...)? You could dress rubber gloves, they with some fur of the mother animal rub, thus it smells of her. Then you had to do the mother first of all in a transport box or whatever act, and then the babies there rausholen thus you can make the nest "new". I hope really this I this have properly understood if nich knows me please on it there.
Laura