Um ... you're welcome.
Put the acros and montis in areas of very good flow and decent lighting. (Since you have a 175W MH over your 20, most places in that tank will have decent lighting, so that shouldn't be a problem.).
The xenia .... can probably be put anywhere. Probably in not too strong a flow, but anywhere from mil to moderate current will be fine. I'm not sure I understand what you mean by "not unshrinking" though? The one thing about xenia is that it can be tricky to move from one tank to another ... it will either look just fine, like nothing happened, or it will "sulk" badly. So hopefully it will be OK, but if not, don't take it personally ... it either transfers OK or it doesn't. If it doesn't, then try again later some other time and hopefully it does OK that time.