Breastfeeding/bottles for naps/weaning

I am still breastfeeding, but at this point it is about 4 times a day. When he wakes up, and before naps/bed.

I work from home Mon/Fri and Tuesday-thursday someone is watching him at my house. I pump at work and he gets a 3 oz bottle before napping. I also come home on my lunch and nurse him.

I am over pumping at work on the days I go in, and more or less pump about 2 oz. Which isnt alot in a bottle for him..

So, my question is do I have the people who are watching him try to give him water in a bottle? Or water in his sippy cup? Or just nothing before naps? He is still rocked to sleep but getting out of the funk these babies habe been in, and starting to be able to be set down awake in his crib again to fall asleep.

I am just not sure how to transition away from milk before naps. He isnt attached to the bottle by any means.