avhdx file growing

Hello

Server 2012 with hyper-v

2 Virtual servers (one DC/File server)

On the D drive, I have allocated 4.7 TB of diskspace

I have a few avhdx files.  I was restoring files from a crash last week (because the Host ran out of space).  I recovered data to the File server (after making a TB of space on the Host).  After copying files into place on the file server, the avhdx file grew to over a TB.  When I deleted files on the File server, the avhdx file did not shrink as I expected it to... so it threatens now to do the same thing as last week.. I currently only 46 GB of HD space on the Host.

I desparetely need to know how to fix this.  I know for a fact that I have cleared at least .5TB off the File Server (guest).

Any suggestions?

Thank You

Terry