this is doable, as long as you have a high number of angelfish and they don't fit in its mouth you can mix them, i've seen set ups like this, they even mix angels/XB and angels/SR.
i hate to break it to you, but your angels are not bred from altums. They may look like altums and it really doesnt matter, but to the extent of my knowledge altums have never been bred in captivity, let alone commercially. I think they may stand a chance if they are large enough