If you want to seed, I'd rake the mulch away before seeding and then top with a very thin layer of soil, just enough to cover the seed. One of the major purposes of a mulch is to deter weeds so mulching over the seeds is likely to interfere with proper germination.

I recall people raking in grass seeds then covering lightly with fine chopped hay. Maybe it was a thin enough layer that it really was not mulch rather a containment for moisture and maybe a bird deterrent.

While what we call "weeds" seed in mulch quite well I'd not rely on that for plant seeds I wanted to grow into good healthy plants.

Rake the mulch back so the seeds have good contact with the soil and then wait until those seeds germinate and grow some before putting the mulch back in place.

A thin layer of straw over grass seeds is supposed to aid in holding soil moisture so the seeds will germinate without repeatedly watering and maybe deter some birds, as well as provide some erosion control. An area was hydroseeded yesterday (seed mixed with a material maybe ground wood, maybe shredded paper, and water) and then covered with the woven straw mats. When that was done around the culvert under my driveway it did not halt the erosion, however.

kimmq is kimmsr