Not sure I understand your question correctly but I saw you didn't have any replies yet so thought I'd post
Do you mean that your LO has a drier diaper if she has less at her BT bottle and you think this leads to better sleep?
I suppose she could be more comfortable if she is less wet although with modern diapers I think they generally feel dry to baby's skin whether full or not don't they?
FWIW I didn't see any change in DS's sleep, we dropped the BT bottle at 12 months, he neither slept better or worse. At just over 2yo though our health visitor did say that dropping the BT feed earlier helps towards night time dryness (although it is not the only factor involved), my DS was day dry and had just started having some dry nights at that time which she felt was helped by having not had a BT feed in a year but instead having his big milk drink of the day in the morning.