Best sippy cup or bottle for breastfed baby?

Lisa

I’m returning to work next week and my in laws will be watching my LO (who is 8 months old) 3 days a week. She is currently exclusively BF and uses just a sippy cup only when she has her solids. She has not perfected using the sippy cup so I’m not sure what I should give my in-laws to use to feed her, I hate to back track and start bottles now. She uses a NUK sippy, any other suggestions on what she can use when my in laws watch her?