Hello,
There is no way to merge two pools together.
One thing to consider is creating a new volume on the Pool that has space and migrating some data from the Pool that is full to the new volume on the other Pool. This will help allieviate some of the space issues until you get the new enclosure. You should carefully consider what data is being moved and how to cordinate that with your future space.
Cheers,
Shawn
I work for Hewlett Packard Enterprise. The comments in this post are my own and do not represent an official reply from HPE. No warranty or guarantees of any kind are expressed in my reply.