In one of my larger tanks, I have seven angelfish who have reached puberty. They have paired off into three groups. It has been interesting to watch the two koi angels pair off, the two blue angels pair off, and the two Siamese/ light blue striped pair off.
The remainder is a koi angel who seems to move effortlessly between the groups. However, soon I may place Alfred (now known as Alfreda) into another tank to try and find a mate there.
I have had angels lay eggs in a tank filled with other fish but they usually do not survive, unless they have plenty of plants in which to hide. Because angels are very compressed (looking at them head-on, they don't measure half an inch even fully grown) they can get into some very tiny places - which means baby fish don't stand much of a chance.
Another option is to place these two koi angels into a tank by themselves, as I've done with Lindsay and Stevie. Koi angels are difficult to find and they are very beautiful, so I imagine their babies would be in demand.