DP and I have been together for nearly a decide. He and his two kids, now agreed 16 and 14. moved in with us about 4 years ago. I live with my two DSs, 11 and 9, in my house which I owned with my ex before I met DP. DSCs moved in, taking a room each, one of which was my office. DP earns a lot less than me and contributes only a couple of £100 each month in rent (which is £2,700 in total). DSCs spend 50% of their time with us and 50% with their mum and have a room each at both houses.
My question is, given that DSD is 17 this year, how long is it reasonable to have to provide her with her own room, especially given that she has her own room at her mum's. I work from home a lot and really need my office back. I am wondering for how long the 50/50 split is tenable once kids are past 16 and have their own lives. Obviously DP will want her to keep a room for as long as possible but, given that it's my job that pays 90% of the mortgage, I really need to take back my office. Also, in London where space/rooms are a premium, it seems really excessive to have a room in both houses (mum and dad) which are only used 50 of the time. Even if I don't use the room as an office, I would like to consider using it for an au-pair for my older kids.