This is for questions about gaining and general upkeep with your bbw.
This is a odd problem I’m having with my wife’s gain . The general problem is that no matter how much she eats and no matter how lazy she is stuck at 266. She looks fatter and her clothes started to look smaller by the day . ( Some back story ) we have been together for almost 3 1/2 years. When we met she was a 206 beefcake softball star. 5 months later she started to gain and it snow balled . Soon she was 260 pounds of tubby melted dough .though for the last almost 10 months she can’t seem to break 270. No matter how much I feed her she never breaks it though. she looks fatter then 10 months ago but weights the same .

You said she was playing softball. Though not the most challenging sport when it comes activity, she probably had more muscle mass than her non-sport peers. It's entirely possible that she's been trading muscle for fat. Muscle takes up less space, so that explains why she's larger -she has more fat now. If you really want to test this theory, get her in a pool. Fat is way, way more buoyant than muscle. She should float effortlessly.