Theres a debug mode option called “link under” that enables this
Iirc I didnt make it default behavior because the linking system is kind of unpredictable. But I recognize that it’s immersion breaking and self bondage is always fun, so…
Eh can you give a bit more detail on how "link under" helps this? I entered debug mode in game menu, turned on "link under", but still cannot put on arm encasing with catsuit, or catsuit with arm encasing. Or maybe this is what you mean by linking system being unpredictable...