anyway to increase the size of a storage space after its been made

I know there isnt a way to decrease the size of spaces, but is there anyway to increase the size of a space after its been made. I have 2 spaces in a pool with the following drives:

1) Backup (no resiliency)

3 tb

2) Storage (mirror)

3 tb
650 gb
200 gb


The first space "backup" doesn't have enough large drives to be fully effective in mirroring. I only need about 850 gb to 1.5 tb of mirroring (have an extra drive that I can add later once everything is setup). The rest of the space I'd like to use without any parity or mirror, just storage of movies, etc (ideally the remaining 3 tb along with the unused 3 tb drive). I couldn't find any way to add drives to a particular space just to the total storage pool. Any way to make this work so I use the hard drives efficiently?

Also, how do you increase the size of a space after its been created? I first made "backup" with the drives in "storage" space. When adding the unused 3 tb drive, there was no option to increase size of the "backup". I wish there windows just showed me the actual size of the spaces instead of theoritcal.