Didn't mean I thought your question was improper, sorry. 'Wrong forum' should have read 'not the best forum for getting a quick and correct answer to your question' (it was late and I was lazy). There's just not many people here who use gear or are willing to talk about it nowadays. It was different a few years ago.
I'm no steroid guru (I just play one on usenet) but WRT your original question: Yes, you can mix deca and test into the same shot no problem (according to my gear using friends). Have I even taken a shot of deca or test before myself? NO - so if you just take my word for it you need to get your head checked
Your desire to use distributed and unmoderated forums is commendable. However, for correct and thorough info from people who've been there, private forums are really the way to go. For example, I'm 'only' using ph's, but the amount of reading up I had to do on cycle setup, dosing, estrogen control and post-cycle therapy (verrrryyy important) was amazing. And none of it could be found here. For real gear the level of complexity has to be several orders of magnitude greater.
If you go to a private forum you can always post the answers to your questions here.
Good luck w/ your cycle.