Tamiya is a hybrid paint. It is part laquor and can be thined with Isopropanol or a small amount of water but is best thinned with laquor thinner.
MM Acrylic is a pure water base acrylic and can be thinned with water or with isopropanol or even a touch of windex. MM Acrylic is somewhat compatable with Poly Scale paint (made by same company)
I have never tried to mix Tamiya and MM. If you are going to try it, mix a small amount and see how it dries.
In general I try not to mix different manufacturers of paint.
Rounds Complete!!