Changing the time signature

I have got halfway through scoring a complex piano piece. I now realise that instead of using 4/4 with triplet phrasing, I should have used a 12/8 time signature. How do I do this without a haywire result? Basically, all I need to do is keep everything I’ve scored WITHOUT the triplet phrasing marks. I have tried the ‘Process Bars’ function without any success. I’m starting to resign myself to the fact that I may have to rescore the whole piece again. Hopefully, one of you geniuses know how I can avoid having to do this.

The only way I can think of managing this is:
In the main Window (not the editor): lengthen the part with the time stretching tool by the factor of 1,5 (e.g. 8 bars to 12 bars, 10 bars to 15 bars) and apply the new time signature. (For playback in the same “tempo” you have to multiply your tempo by the same amount (e.g. 120 bpm become 180 bpm).
(Sorry for bad English…)

What SV said is about right.

Also check out these post from the inestimably wise vic_france (rip Vic).

https://www.steinberg.net/forums/viewtopic.php?t=21371
https://www.steinberg.net/forums/viewtopic.php?t=15710

These are from a google search, thus:
site:steinberg.net/forums time sig 12 vic_france

It’s just maths.
Thank you SV, thank you steve, and thank you Vic (I know your hear us :wink: )