I remembered that u should have 2 maids (1 Indo + 1 Phil), Indo maid mainly do housework and Phil maid mainly take care of twins, so I could understand how handache if the Phil sick.
How about force the Phil maid that she have to wear mask and change the job with Indo maid (i.e. Phil do housework) until she completely recovered.
U send her to doctor few times already, and finally suffered to the whole family, you should "do something" to show that you are serious on this matter.
I doesn't mean that you should shout her, but if she still not follow the doctor's instruction, her body will became weak and might affected by serious deseases after her holiday (meet with her friends), and this is a bad cycle.