These underpants have 3cm (1.8inches) of fabric in the crotch (not counting the flimsy lace), so they really are not suitable for using with a cloth pad.   As you can see in the image, if I tried to use a 7.5cm snapping pad with these, the sides of the underpants don’t come out to the edge of the pad.  So there is nothing stopping the pad from sliding forward and back, or even rotating around.  This pad would slide around like crazy in these underpants.

With these underpants you can see that the underpants crotch width is wider than the pad would snap.  So when the pad snaps around, the extra fabric of the underpants “bunches” up.  This is actually beneficial – as it creates more friction to help keep the pad in place.

Another problem happens with pads that are straight with no flared ends, worn with narrow crotch underpants. If the pad isn’t flared to the same sort of shape the underpants, and aren’t snapping firmly around the crotch, then they are more likely to slip sideways or the longer back end can slip out of where the leg hole is.  Flared end pads not only give more coverage for leaks, but they also have more surface area to be held in place by your underpants and are less likely to slip around.  They are also less likely to give you a “wedgie”