BBL and also fat transfer to the hips - How to sit and sleep?

I'm hving my BBL and just booked also for fat transfer to the hips, I know it's no sitting down for 2weeks and lying on the treated area for 4weeks,after that can I lie on my side as tht is how I normally sleep? And also I'm paying a lot for my surgery is there anything I can do to make sure as much as the fat survives as possible,apart from not sitting for two weeks and not sleeping on the area for four weeks? Thank you for any advice :)