Did you call Sonic I am pretty sure you can schedule to have X2 installed in one visit if you do call them and tell them you want X2 ... I never ever had a problem with the X2 installations one phone call was all it took and the order was placed ...
The migration from ADSL2+ to VDSL2 is a "frame re-wire", it's all done in the central office. And, that's one discrete workflow, and it needs to be completed before we can assign a second port on that card, deploy a new pair, etc. So, I'm afraid for now at least, it's two processes, two support interactions, etc.
Over time, as we continue to streamline operations for efficiency, we may take up merging these two processes into a single work flow, but for now our teams are totally booked up with other work around FTTN, Fiber, etc.