Louise that so wonderful to hear! Like you I have close the amount of designs that you have from several sites. At this time I have them on a usb flash drive that has a large memory capacity. Let us know the outcome!
Bjhumes, I have used iron-on stabilizer. Knit fabric tends to stretch though at times I have also used Sulky spray on the cutaway for knits. For onesies since they are small I have found that using the iron on one (they do peel off after the design) works. Also I used Floriani no mesh since it is soft on the child's skin. There are others here that may have other ideas as well.