Best way to sponsor ex-helper's visitor visa

Hello,


We just let our helper go for financial reasons (one of us lost work, so can stay home and we don't need our helper anymore). However, we had a good relationship with our ex-helper and want to make good on a promise we made to her to have her daughter come to visit during Xmas (she wanted this rather than going back to the Phils for her vacation in the last year). We would like to have her daughter come to visit for 3 weeks in December and would allow the two of them to stay in our house while we go on vacation.

I'm wondering what method would be best to sponsor our ex-helper's daughter to come here for the 3 weeks? Would it be best for us to write a letter that the daughter can present to immigration, as well as the ticket she'll have leaving Hong Kong in 3 weeks? Or if we are not the employers anymore, would it be a bad idea for us to write this letter?

We are thinking about buying the ticket for the daughter pretty soon, so want to be very sure that the daughter can actually use the ticket to visit her mother as we've promised.

The daughter is 20 years old and is a nursing student.

Does anyone have any ideas or experience like this?

Thanks.