Premium tabs and remove only tab upgrade priority question

I want to buy more premium tabs, however I want to control which remove only tabs are changed over, can someone tell me which remove only tabs are changed over the beginning or the end of the line in terms of closest to my current premium tabs...

IE my stash goes

[Premium Tabs---------------------------------][Remove only tabs-----------------][Race rewards---]

You can also re-order your tabs (including remove-only tabs) by clicking and dragging them from your Stash window if you want to separate them out like that.

The script that controls what remove only tabs get converted is obviously not straight forward, in that it looks on first appearance to choose at random which remove tabs (and how many of them, when purchasing a bundle) get converted. I've discussed this process with friends to get accounts of their experiences and have developed a theory that the tabs may have some sort of date code and that this is taken into account when tabs are converted from RO. This means for example that if you upgrade standard tabs to premium tabs, the tab that's chosen is the oldest standard tab you have, which could be a normal add/remove tab, or it may just as likely be a remove only tab that's been sitting in your account for some time.

I'm unable to prove this theory as I've long since shuffled my tabs around and no longer have any idea what the age of my tabs are, but in light of GGG not seeming to know, it's the best I can come up with until a full explanation is forthcoming from GGG.