All the above is good advice… I just want to clarify that she is not just moving in with you, but is also moving from another country where she has been attending private school?
In addition to the awkwardness of being strangers with you and your husband, there may also be some culture-shock issues at a socially vulnearble age for most teens. Help her prepare for the adjustment to a new school, and whatever differences there might be with the kids in her new school from where she was before.
She has probably created some degree of escapist fantasy about this change, as disenchanted teenage girls will do, and she may well have no clue what to expect. Be straight forward with her… tell her that you’re nervous about getting to know one another and getting comfortable as a family (~don’t let her see that you’re scared, though, they can smell fear~).
Do express that although you acknowledge that she is no longer a little girl, she is still a minor and you are accountable for her (my son got tired of hearing, “Mommy is not my name, it’s my job title”), and therefore there will be rules and expectations. Make sure she knows which ones are set in stone (e.g., no drinking, or smoking, etc.) but that as long as she can present her side clamly and respectfully, you will be willing to listen to any suggestions she has for modifying some rules.
Also be clear on what your rules will be regarding her spending money and expenses… teenage girls tend to enjoy shopping, so if she must do chores and/or maintain a certain GPA in order to get an allowance, make those terms clear. If she can get working papers at 14 where you live (that’s the youngest here in NJ), discuss the reasons why you want or don’t want her to get a job outside the home.
Make sure to let her know that you adore her, and are looking forward to developing a close relationship, but that you must have those rules for her protection because you love her. She might try to manipulate you and your husband, or even work you against each other. She might even do the same with your ex and even with her brother… I am not saying that all 14-year-old girls are evil; but they are hormonal, and this child has been exposed to some level of manipulations since you say that the kids have been lied to about you.
At the same time, recognize that on a level that she may not admit to herself, she is afraid, too. Ask open-ended questions, and offer to be totally honest with her about the past and what your side of the story is, but let her ask the questions because you don’t want to overwhelm her.
Your situation is highly complex, and teenaged girls are the most complex creatures on the planet… I wish you the best of luck!