Room sharing

We are expecting our second little boy this June & we’re planning on having him & his big brother, who will be 2 years old this August, share a room once the younger one is old enough to transition to a crib. Now my mother-in-law is saying to have 2 separate rooms for each boy, but we don’t have the storage to get rid of everything in the guest room to convert it. So my question is, so any mamas in here have experience with their LOs room sharing & can give advice? Thank you in advance 😊!