Stepchildren and Bedrooms

The are 5 and 3 so I don’t think they are will care if they have a smaller room at that age.

We have 4 children and live in a 3 bed. My stepson and my son share, my step daughter has her own room and then we had the largest room (with a window either end) and ws able to partition so my daughter who's almost 2 now has her own room rather than sharing with us or her 13yr old sister. We had a stud wall with a sliding pocket door

I think you can mix bio and step kids bedrooms, the sex of the children is the biggest thing. So ATM your 6 month old has their own room. But when the next LO comes you can make the choice based on the sex and age of the children based on needs. For example currently why disrupt the older kids sleep with a 6 month old but later down the line they'll be best friends and you could have a girl next that would get the box room. Even if you have another boy then the two tiny ones don't need the same size space as the 3/5 year olds do, I personally think that as they age up their needs and wants change so go off that as you go. When you have a 10, 8, 5 and 3 year old then the 10 year old will more likely want their own space and the other three share a bed/play room. I think room ownership should be a fluid thing as to needs.

We used to have a 3 bed, so it was our room, girls room and boys room (2 girls got the small room, 3 boys got the big room). We have had a 2 bed for 3 years, the step kids have always shared the other bedroom. However the older ones have moved out or don't want to sleep over at dads anymore. Now we have a 6 month old my 15 year old stepson has said he'd rather sleep on a sofa bed and have the space for his computer and clothes etc in the "kids room" instead of actually sleep in the same space as his sister as she is so much younger and not the same sex as him.