I don't have experience with any rotary cutters other than Olfa and Fiskars. The Olfa cutters have notches or sprockets in the center, and the blades are shaped the same way at the center hole to fit. I think the Fiskars and Olfa blades can be used interchangeably, but I don't think it is good for the cutters. Those center posts are only plastic and will wear with use from the pressure during cutting. At least that has been my experience, so I don't aggravate the situation by putting the wrong blades in.
Enjoy your charity quiltmaking! The people who receive your quilts will be so thankful!
Dayle
Concerning donations -- you will want a receipt for the goods given, but don't expect them to place a dollar valuation on the items. All they will do is verify what and when you gave something and sign off that nothing was given to you in return. The agency must be a 501c3 organization / have an IRS recognized non-profit status.