My daughter had filed petition for my son under brother and sister relation in F4 categories. The priority date is February 11, 2008. The petition is approved and received bby NVC on Feb 24, 2010. I was also, sponsored by her, and am citizen now. Please advise me, if, I can replace my daughter as a petitioner and change the status of file to F3 categories? and what will be the date of priority? if permissible. Kindly advice me the forms to be submitted and mode of payment of cost, if any.