In the Japanese version, he said "見ていろ,子供達…" (miteiro, kodomotachi).
At first, we thought that this line was referring to the other Holy Knights members who are clearly young. This was also the line of thinking of the fan scanlations (TCB). But this might not be the case.
The Japanese speech by Garling here when he refers to the "children" is very polite (kodomotachi). If he wanted to be rude, he would refer to the other young Holy Knights as "kozō domo" (小僧共) or "gaki domo" (ガキ共), but he did not use those terms.
So the context here is that Garling might be conversing with his own "children" (plural). It is heavily theorized that Shanks is Garling's son (no official confirmation yet) because of how they look alike and that Shanks was found as a baby in God Valley by the Roger Pirates. Also, the hint in OP Film Red that Shanks is from the Figarland Family (Garling's family name).
Since Garling specifically said "kodomotachi" (children in plural), this implies that if Shanks is the other baby, there could be another baby! A twin perhaps? The Shanks that we saw in Mary Geoise conversing with the Five Elders might not be Shanks after all, but his twin. Only time and Oda can tell.