Hi, thank you for your question. In order for the children to travel abroad she will need your consent for this as you have parental responsibility and without any written consent they may be stopped at the border and refused travel.
In relation to her new partner, unless you can evidence concerns or risk towards the children it would be difficult for you to persuade a court to restrict his movements and prevent travel abroad with them. If you are able to demonstrate this then you can apply to court for a prohibited steps order under form C100 and a £215 court fee to the children's local family court and the court will consider whether there are grounds to prohibit the children travelling with him.
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