Have a grandparent open an RESP and put everything in there. Easiest solution. As for the SIN number. You can request a copy.
Which grandparent? His mom? Is old and would definitely drain the RESP, because his sister has POA over her affairs and she (his sister) helped him fuck me over financially (they're both accountants).
My parents? He would never allow that.
If you request a copy- they'll ask you why. If you say it was lost- they issue a new one.
I took rocksan's advice and let him know if I don't have the letter or a copy of it before the week's end. I'll report the number as missing next week.