There has to be a solution to my problem

[baldrick]

my chooks are pets too so I know what you mean. TBH if she is carrying mycoplasma they all are, so Id say only cull her if you feel her quality of life has dropped to the point she has had enough (or just before) as if she was a dog or cat, but culling her to stop new ones picking it up wont work unless you do them all. tender belly sounds like egg peritonitis or sometimes they can retain an egg for a long time and it eventually kills them. Id say get her to a vet who is used to pet chickens as a general farm vet will always advise to cull because treatment is labour intensive and not cost effective. Hope you are ok with whatever decision you make x

[RichmondHens]

Thanks richmond, I can offer them a separate coop but the run would be the same, which I had planned to do.

Then you might as well put them all together, if the hen house is big enough. If they are to share the same run, drinkers, feeders etc then they might as well all live in the same house and be easier for you to manage.