PaddedCube,
If you are willing to order online I would recommend the Tranquility Premium Overnight pull-ups for someone with moderate stress incontinence. They have internal standing leak guards and hold 34 ounces. The 34 ounce capacity means that the lady will not have to rush off to change as frequently. Don't worry about the "Overnight" in the name. I am incontinent and have worn them for daytime use. They also are thin and very discreet.
If purchased by the case, Magic Medical has them for a very competitive price.
--John