Altering a flowering plants light cycle.....

I've got a friend who is in a dilemna and needs to significantly downsize his garden. He is wanting to bring them into my flower room as space in not an issue with me.
Problem is his ladies are on a 10AM-10PM lights on cycle. My room is literally the exact opposite, 10PM-10AM lights on. Both rooms have Co2 enrichment. My room is 6000W vs his 2K.
The strain is Tangerine Dream which I have no experience with. The ladies in question are roughly 4ft tall and have been in flower for 3 weeks now. They were vegged over 4 weeks and are pretty large at this point.
I'm very leary about this for many reasons, but frankly I have no idea what would happen. My biggest fear is not them dying, but them herming out and hosing my garden. My friend is pretty much set on doing this, I however am not.
What do you guys think would happen?

*hi'gh. sorry about moving your thread out of AMC, but i feel you would get more in-regards to your Qs in this forum. thank you for posting @t RIU

--cheers

Thanks wizard for taking me to the right place.
I'm thinking my best bet may be to try to alter the light cycle by 1 hour each day for 12 days until I'm at the desired cycle. I could move them in and out of my veg room and a dark closet till I'm there.
Anybody have any thoughts on this?

Hey bro. Last grow I actually had to alter mine twice my last grow due to power outages. Once I completely flipped as u would be. I'm not the most knowledable grower but I didn't have hermie problems. I'm sure they stressed a little but I gave em 24 hours darkness before they got restarted when I flipped schedules because that's what mainly fuels flowering is at least 12 hours of dark. Maybe this will help u a little bro.

they will be fine, don't worry .. no reason to panic at all .. once you move them into your garden, they will simply adapt to your 12/12 cycle you wont notice any problems caused by changing cycles like this on just 1 occasion ...
if you were to keep changing it back and forth, perhaps it would stress them. but since this will happen only one time, i cant see any possible problems