If both of you are listed as equal owners that means half the condo is yours and the other half hers. If she passes away without a will, her half goes to neutral heirs: 50% of her half goes to you as the husband (so you already have 75% ownership of the condo and basically everything else you bought after you got married). The other 50% of her share is divided between her children and other surviving members of her family ie parents and siblings, so in the worst case scenario they can claim that part but they have no claim over your 75% of the property. It might be better to have a will, but they might also challenge the will at court.
Nothing to do with Thai\foreign quota