I am in the process of painting my kitchen cabinets and I am experiencing some brownish stains seeping through the paint. I would appreciate any input or advise on how to fix the situation.

So far I have cleaned the oak cabinets, sanded, used a grain filler, sanded, primed using a water based stain blocking primer, sanded, applied one coat of Ace Door Cabinet and Trim paint. (I am planning on doing 2 more coats of paint)

I am now discovering this brown stain coming through is due to tannins in the wood, and ideally I should have used a shellac based primer initially. I am wondering if I can now use the shellac primer over the Ace paint (alkyd enamel) and then continue to my final coats of paint? If so should I do two coats of the shellac?

Thank you for your help!