I've let Angel pairs keep their spawn a few times.
- When you see the female start to look gravid with eggs, do a water change and relocate the other fish
- You should only be running a air pump driven sponge filter at this point.
- Black water tonic, or a single Lypton tea bag(very old school) & raising the water temp will push the spawning.
- cover the glass with brown paper from a grocery bag. You can cut a small peep hole.
- Lots of hidding places for the fry, Java moss, hornwart.
- keep the parents feed
- have brine shrimp eggs ready to hatch. I've also used infusoria
http://aqualandpetsplus.com/Live Food, Infusoria.htmc I would feed that into the sponge filter and fry will feed off of it.
- Be careful not to photoshock the tank
Losses are going to be high vs.raising the fry in by themselves but, it is worth the effort.