Birch grows like weeds here; they pop up in sidewalk cracks, rain gutters, rooftops, wherever.
But the protocol is about the same:
Soak in 1 cup of water with 1 tablespoon of 3% hydrogen peroxide (straight from the bottle) added to the water.
Soak for 2-3 days, change the water after day 1.
All sinkers can be sown, the rest can soak for a longer period if you want. Maybe there are a few late comers.
Put some pumice or perlite in a ziplock bag, make it damp. Drain all excess water. Make 3 bags for each type of seed, because if something happens to 1 bag, you'll have 2 left.
Add seeds, put in the fridge for 2-7 weeks at 5 degrees C. Check every 3 days if there's fungal growth. If there is: open the bag, let it breathe for a day or 2 at room temperature. Add a dash of peroxide to wet it again. If they aren't actively germinating, they can withstand a wet-dry cycle.
Then sow the pine seeds 0.5-1 cm deep.
Sow the birch on top of the soil, cover them lightly if you want so they don't blow away but 3mm of soil should be enough; they don't have a lot of storage in their seeds because they spread through the wind (with a relatively tiny wing compared to pines). They don't have the energy to burst through the soil like pines do.
Spray it down lightly with some water. Put it outside and cover it to keep birds away, screw humidity domes because they'll bake whatever is inside.
Or sow them all together in a tray at the beginning of winter. They let nature do its thing. I did a cold stratification this year outdoors by sowing in January.