How to position subtitles in an SRT file?

I have a project that has been broadcast that is now going to BluRay and DVD.    We created SCC Closed Caption files for the broadcast which included screen position so that the subtitles did not occlude lower thirds - if there was a lower third, the subtitles popped up to the top of the screen.  But now, we need to deliver SRT files for the DVD creation, and the SRT export of the SCC captions does not include any positioning info - it's all at the bottom, and now overruns lower thirds and credits.   From what I've read, there are a few 'sub' SRT formats, such as .ssa and .ass which do allow title positioning.   But what I'm reading suggests that this is entirely unreliable across tehcnologies - they may be repositioned correctly in, for example VLC on your computer, but will not be positioned correctly on a regular old DVD player.   Any thoughts from the hivemind on my best approach here?