Preferred Stock No./Pre-paid Account No.

I'm adding my kids to my trust via UCC3 and I wanted to see if anyone on here has done it before so I could make sure I'm getting all the right numbers. I'm pretty sure I know but I don't wanna call SFS if I don't have to. The document calls for Certificate of Live Birth No. - check, got that Social Security Account No. - check, got that then ??? associated Preferred Stock No./Pre-paid Account No. ??? ^ I'm pretty sure this is the number in red writing, begining with a letter, on the back of the Social Security Card right? Thanks in advance for your help!