Find out if she is prepared for the worst (being sent back home). In that case no amount of tactics applied will work. Else let her understand what it means being terminated (2 years ban, perhaps she is not aware of). Then brief her in a matter of fact manner what and how you want things done. Tell her children don't lie and they must be happy with her. Assign her a probation period and give her a chance to improve. Have little patience, praise her for something that she has done right. After all she is a human and most probably she will improve.
If even then she doesn't then you know what to do. At least you will not be in a guilt then as you are now for sure.