I find that Grass-B-Gone is excellent but only for most grasses. I get them mixed up but the grass that spreads with runners is gone in about 2 weeks.

Eventually, you will be left with the grasses that it wont kill.
You might write to the company to get the list of what it kills and what it does not. If you can identify the grass, then there is a list on the bottle you can check.

Depending on the size of the area, you can spray one section and see if it affects the plants you want to keep.