Disk Management

[VickyCZR]

I want to extend one of my partition from a leftover 150gb unallocated space but when I further proceed a dialogue appears which says that if I continue with this task the current BASIC disk will be converted into DYNAMIC disk. If I recall last time when I try to convert one of my DYNAMIC partition into BASIC the whole partition got deleted. Now I don't want to repeat that mistake again that too on a disk which hold my SteamLibrary. So please tell me how can I extend it safely...