From my experience best way is to send an e mail to FMG Oleg, (the manager at Aspens ) and Vladimir the director guy at FMG in sofia. Also to Andy Peach at MRI. Tell them when you will arrive (if in the middle of the night like us they give the Key to security guard at Heights other wise I presume in normal hours you would get keys from reception at Aspen golf. Tell them you want to sign your POA (but will be making alterations) and ask them to contact Legal Independence for you and make sure the deeds are sent to LI Office in Razlog for collection. (we did this but they didnt do it , we called in at LI office and they had deeds from sofia in two days)
Oleg will give you a copy of POA. You will need to tell him what items you want removed. He wil later give you an amended copy with the changes you requested. He will make an appointment for you to see the Notary in Razlog and arrange for a translator to be present. Oleg will go with you in the FMG minibus along with Boris the driver (great bloke very helpful). Translator will translate the POA for you and make any slight alterations if required. You will then go into see notary who will witness you signing the document.
That is basically it . Translator will cost 20 lev, the notary signing will probably cost just under 11 lev. It is quite painless and inexpensive

We didnt need proof of ownership
We used furniture box in Bansko for our funiture, bloke called Eddie or Stanford. Couldnt be more helpful. Now own a furniture factory and will do bespoke furniture at very reasonable prices
Hope this helps Will post more after I get home. But have to say we are delighted with the Heights complex and our studios. Swimming pool and Jacuzzi still having teething issues but I would expect them to be functioning when you arrive. We have been the only people stayinh there for the last three nights!!