I hope you can get you mum and DH on board, it will make things a bit easier for you.
You can certainly use PU/PD although at this age you need to not do the PU part! We did it with both kids, we had a sleepy phrase and just repeated that over and over (it's ok, you are just going to sleep/ lie down, it's time to sleep), if they stood up we (me
) were sitting on the floor next to the cot so it was a case of patting the mattress to get them to lie down. If they got very distressed I picked up briefly but it's better not to. I continued to shh my two and I would put a hand on them through the bars or stroke their face.
Good luck with DH!
Laura