Why make the blocks or the quilt first?
Why not make the portions that need the signatures .... use washed tone on tone pale material [prewashed without any additives like softener and ironed] with something like freezer paper ironed on the back and make template to put over this so that the signatures are well within the seam allowances. You could use plain file folders with the area for signatures cut out ... making this template the same size as the material to be written on. Then provide written instructions so you mother can enlist the aid of others in getting all the signatures. Either provide the pens or have your mother buy them to take with her.
This has many advantages. Less bulk to transport. No real errors on the finished quilt since if someone does make a 'boo boo' they can simply try again on another piece of signature fabric. Also, You could send fabric to those folks who cannot make it to the reunion due to illness or other problems, so they are also included.
That give you plenty of time to think of how to make the quilt and quilt it.
I just made a little signature quiltlet using the square in a square method ... the signatures were on the center of the square. The recipient loved it!
ali