When I was a bachur, I was told that Reb Aharon Kotler zt”l had guaranteed that someone who moves out of town will not lose his children.
Then I was told that he made a condition: that they go there lishmah.
When I got older, I asked Reb Shneur (his son) z”l if the rumor is true.
He responded that he never heard it from his father, but that it makes sense that he would have said it.
Both the first part and the second.
Reb Henoch Leibowitz zt”l also sent talmidim out of town and assured them that things would be fine, based on a Seforno at the beginning of Parashas Chukas.