It's most likely that the guppy died and was eaten afterward unless they were very small guppies. As for adding more fish, really the YoYo's ought to be in a group of 6 and the Black Phantoms would benefit from being in a larger group; shoaling fish always look better in bigger groups.
she searched for two days and it turned up inside the filter housing that covered the impeller... it was just chilling there catching food as it went past. something tells me it would of been more than happy to live its life sat there too lol.
Either its been eaten post dieing or it will turn up. Either way i feel your pain. I'd personally remove the guppies and bulk up the groups of fish you have. Add some yo yo loaches and a few of the phantoms to really let em shine... I'd also identify the gender of your pearls and perhaps add a few more... 1 male to however many females you want really. But thats just me.
Either way, good luck in your search and good luck in your hobby
definitely unfortunately sounds like it was eaten to me, or it died and was eaten, Im sorry for your loss
My 6 guppies are a few months old and just started breeding, I found out after noticing a small fry after doing a water change, put him in a fry container but he died a day later, Since guppies breed insanely fast, I think they were definitely more guppy babies, that unfortunately the parents ate after giving birth to.