Tier 1 general dependant visa - change of surname TOP

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Hi

My wife recently came to the UK under the dependant category of Tier 1 (General) Visa. Her 'Entry Clearance Visa' was obtained with her old passport where she had her maiden surname. The entry clearance visa was stamped on her passport and although her biometric details were taken when she had applied for he visa (3months ago) - she didnt recieve any biometric card.

Since her arrival to UK she has gone ahead and changed her surname in passport by adopting my surname.

My (our) leave to remain under Tier1 extension application is due in 9months time

My questions are these:

1. Does she need to obtain a new biometric card since her change of surname? Or, will it suffice if she carries her old passport as well (on which there is the entry clearance visa) when travelling through border?

2. If answer to Q1 is 'No, she may carry on with her old passport' - then will it affect our application when I apply for extension in 9months time?

3. If answer to Q1 is 'Yes, she needs to apply for biometric card now that she has changed her surname in new passport' - then which form do I refer to? (application of replacement biometric residence permit? or TOC form?)

Thanks for your answer...

Regards