Tenants in Duplex asking to use garage as storage.

[Frank Martinez]

Hello, Just acquired my first duplex. It has a detached garage, two separate, one car spaces. I had plans to use one as a gym, and one for a recording studio. The tenants in the front one bedroom are asking to use one as a storage as they have a second baby on the way. 

My gut says no, but I wonder if its just a few plastic bins with baby stuff, maybe charge them a few bucks to store them against the wall near the opening door. 

Is this a problem waiting to happen? Should I just say no? 

Is it tacky to charge them money just to store a few plastic bins? How much should I even charge?

This is all new to me and I really don't know anyone who has experience on this. Thank you.