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https://www.gov.uk/change-circumstances-visa-brpCan you please provide me the link of the form you mentioned?
As I said, curtailment letters are not sent out instantly when HO is notified of your last date of employment. It takes a while to go through the process.Also, how would I ensure that the curtailment letter has not already been sent to the wrong address? Is it by asking them a letter or something?
The link is quite clear. If you apply for a new sponsor then your dependents do NOT have to apply if they have sufficient visa left.