I'm no expert Rosalie. There are some on here that is a whiz. But if you want to reduce the pattern from 15" blocks to 12" blocks, you would reduce by 83% using a scanner or copier.

The calculation is New size / current size x 100 = % to increase or reduce

Some of us use the program EQ (Electric Quilt) but if you don't have it, the above calculations should work.

You can downsize a quilt block the old fashioned way by using graph paper. Determine how many units are across by the number of units down. Multiply these two together to determine how many units make up the block. Example: a nine patch is 3 units across by 3 units down. 3 x 3 = 9. Draw a 12! block onto the graph paper and divide into the correct number of units. Now draw in the angles to match the original block. You have a downsized block. If you post a picture of the block, I am sure several people would be able to help