Whatever you install you will have to remove or they will remove it at your cost when you leave the apartment.
Emails won't get you much far best to talk on phone or face to face. Nakheel have property management office in gardens inside ibn battuta mall.
As most people know Nakheel can be a nightmare.
I have emailed them to ask whether it is allowed to add invisble safety netting to my apartment balcony but had no response as yet. It is quite expensive to have installed so i dont want to have to remove it.
Has anybody had any experience with this? My balcony is probably already about 4.5ft high and has approx 4.5ft open
Thanks for any advice :)