So i set the whole song to half the BPM count (158 to 78). Reduced the chord duration length by 1/2. Then set the half-times RTs to normal and normal timed ones to double. Funny is through that some wouldn't adapt. (freezze is off, re-generated the lot) F.i. RT 1579 Banjo Rhythm plays a the same tempo either at normal time or half-time. Double speed then quadruples the speed, as if the conversion algorithm doesn't work right .... I'll have to suss this out further, but my personal time frame right now fails to let me spent more time on experimenting with this untimely messy BIAB feature.

One Q: is there a general setting for half time for a whole song somewhere?