I usually find that cichlids which look different from each other, be it coloration, mouth or body shape, have a better chance of cohabiting, than those that look similar. If cichlids look similar, they often see each other as competitors, for food, breeding sites, mates, etc.
Lyonsi and Vieja are different enough from each other (especially as adults), that they may actually make a go of it.
I kept lyonsi and Vieja melanurum together with little problem in a similar size tank.

the difference in mouth shapes suggests relatively different diet choices in nature.

I had similar luck keeping bocourti together with Chuco intermedia, although color was similar, body and mouth shape suggested a different diet preference, as adults.

The obvious similarities in species of the same genus usually leads to conflict, or hybridizing, and is much of the reason I don't keep species of the same genus, like two species of Vieja, or two species of Parachromis, in the same tank