Use strap arches hold straps or handles in place. You can even use strap arches to attach handles to your bag.
These are extremely easy-to-add and very strong. All of the components to create four arches are included.
Simply cut slits for the prongs with a seam ripper, then poke the prongs of the arch through the slits, add a washer to the backside, and lastly bend the prongs outwards.