How can I persuade 17 month old to sleep in cot all night

[busterised]

DS goes down fine since we did some sleep training but wakes every night about 10.30-11. Settles well after some milk but only in our bed.
Needing milk has just been last few weeks and suspect it's because bedroom gets quite warm, before that would settle but again only in our bed. Would really like to stop co-sleeping but he shares a room with DD 3 and worried he'll wake her when he's unsettled.
He's still in cot but will be moving into toddler bed in a month or so.
Any tips on how to settle him? Suspect it may be us as also co-slept with DD until she was 2ish. She stopped when she moved into a bed.

Is there another room so he can go in his own room? If not, it's just unfortunate as the only way will probably cause a bit of bother.

What happens when he has this milk? Does one of you go into his room and hand him a bottle? Then what happens?

He has the milk in a sippy cup and if in our room will settle quickly in our bed. If we give milk in their room he tosses and turns and eventually starts crying and won't settle til we take him to our bed.

So are you putting him to bed in your room? Or in his?

We had been settling in our room but last few nights have been giving milk then putting back into cot in their room. Having to take into our room as not settling though.

Give milk in his room, with low light. Sit in a chair with him. Then put him to bed.

If he doesn't settle, just shh him for a bit...then if he carries on, pick him up and comfort him but don't leave the room or speak too much.

Put him back.

Repeat.