CSPA for derivative applicant family?

[motopokep10 0]

Hello.  I am a US citizen, filed I-130 for my adult married son in August of 2010, petition approved in April of 2014, so pending 3.59 years. Visa number in the F3 category will be available in April of this year. My granddaughter will turn 21 years of age in mid-April. The earliest the visa interview can be scheduled is end of April after she will turn 21. Will she age out or not? According to some sources I read, the principal applicant's parent's interview must occur prior to derivative applicant's 21 birthday for derivative not to age out. However, USCIS website has information that CSPA also applies to derivatives and to subtract the number of years the I-130 has been pending from their age at time of interview, so does that mean my granddaughter will not age out as her CSPA age will be 17.5 years at time of interview? Thank you.

[Boiler 46,604]

Not