Which plant to use for my tropical mixed lawn? Poa? Oxalis?

[forest1227]

Here is the picture of three types of grass currently growing in my garden. Are they Poa spp.? Which one of them is more suitable for constructing a low maintenance lawn in the tropical rain forest? I might want to add Oxalis corniculata to make a mixed lawn. I added Oxalis corniculata to Bermuda grass before, the result was that Oxalis crowded out Burmuda grass. Is that going to happen again? I hope the experts will be able to help me.