It sounds like the OP had a LO who was upset about feeling wet at night. Many fleeces let moisture flow right through and keep the surface feeling dry. The absorbent stuff is below. Just like any of our pockets or AIOs with material inside that feels dry.
So... You can just cut fleece in the shape of a liner and lay it in.
A few fleeces repel, and some repel in one direction and not the other.