Currently, when moving clips with transitions attached, these transitions are not intelligently merged.

Eg if there are clips ABCD with cross fades between (so AxBxCxD) and clips BCD are selected and moved and appended to clip P, the dissolves move too BUT the first one becomes a fade up from silence. So PvBxCxD - where v is the fade up from silence.

The GUI appears to show a cross-fade but it's actually a fade up from silence.

Look at how Avid deals with this - the replacement cross fade is always pretty intelligent (even when both sides have transitions).