Share one SSD Cache across multiple volumes & storage pools on Synology NAS

I have a new Synology NAS with 2 storage pools, and I have one volume per pool. I have added a single SSD to the NAS to serve as a cache, and was able to add it to the first storage pool. This is a fairly large SSD (4TB), so I would like to share it with the second storage pool. However, I am unable to add it to the second storage pool. According to the Synology Online Guide "SSD cache group supports cache creation on multiple volumes". Perhaps I misinterpreted this statement! Can I use my large SSD to provide caching for multiple volumes, across multiple storage pools? (I can't believe they want me to add 1 SSD for each storage pool) I'm using a SATA SSD in case that matters. I read that (I think) I can use NVMe card as cache instead. Does that behave the same way? (There are only 2 NVMe slots, so that would mean max 2 storage pools can be read cached, or 1 storage pool r+w cached).