Now the ITV owns the GMTV time slot is there anything that would prevent them from having a programme start in the GMTV time slot (eg. 9:15am) and continue into the ITV1 time slot (eg. until 10am)?
Well, they have done this before, at the very beginning of GMTV in fact in 1993, when The Disney Club used to start at 8.55am and continue all the way through until mid-morning. It wasn't the original plan, but the original weekend schedules of GMTV were flopping, so they launched this idea in March. STV, who produced it, and of course Disney were both shareholders in GMTV it was probably easy enough just to extend it.
It was all seamless, the first half hour was basically just a cartoon with links either side of it, then they'd go into a break at about 9.23 and come back at 9.25, there was no start-up or anything (and no link at the start of the show, it began immediately after the ad break). That lasted until the end of the series in May, then in the summer they did something called Disney Club Summer Holidays, which was just cartoons with short links from the Disney Club set, in GMTV entirely. Then there was a period when the Disney Club became ITV only again, but then around 1995 it became one show again from 8am to 10.15, although the bit in GMTV was often like a separate show, filmed on location, with only the 8am link coming from the studio.
I know a bit too much about the The Disney Club. One thing I'd like to see with this change is that it stops finishing at 9.25, which is an annoying time, nothing else starts or ends at that time. There used to be a reason why TVam ended at 9.25, so the regions could do news before the schools programmes, but that stopped being an issue over twenty years ago, so why they can't round it down to 9.30, which would be less messy, I don't know.
(and to a lesser extent UTV, although they have very similar branding anyway).