I moved my then-3-year-old from Michigan to Ireland, and then we abruptly moved (the now-5-year-old) back to the US last year, to Texas. I fully agree with the opinions given so far.
Our son is very social, and has "many best friends." (his words) In all cases, he was much more interested in looking forward / meeting new people / seeing new things than thinking on what was. In the cases he did ask or otherwise show interest in his old life, we did reach out. We secretly kept in contact with old friends' parents, teachers, etc. to let them see how he was doing, and be available to help their kids' adjustment, too. We also offered opportunities at normally nostalgic times, i.e. send Christmas cards to former teachers. But followed his lead. Leaving Ireland was a little more difficult, as first Covid isolation cut off in-person contact with school friends, and then our move was relatively abrupt. But he went to an international school there, so leaving / new kids arriving was a fairly common occurrence, and the teachers there facilitated a goodbye party, although virtual.
Maybe your oldest will be hit harder by the move. But whatever happens, it will pass, of course. Give her opportunities to anticipate / participate in the new situation, and opportunities to keep contact. It will be much better than if you were moving teenagers.