how to vary FLR FP application to flr M

[Miangee]

Hi all respected members
I am a british citizen got married 4 months before
my. Husband was student and college revoked i have got only 4 slips before end of my husband 60 days

So i am just submitting flr FP application and then vary application after geting 6 payslips

Can some one plz explain how to vary the application
is there any form or just cover letter

Shall i need to pay fees for flr m again as both apllication fees are same and if i pay again at the time of vary will HO refund first fees after vary

What about the biomatric shall i need to give again after vary the application
and shall i received any confirmation that application has been vary
plz guide
thanks