There are several issues here. One is whether waiting 30-40 years to enforce a support order would be barred by the Doctrine of Laches. There is no statute of limitations relating to support but something similar, Laches, may prevent enforcement.
And, here is the other question: who is entitled to enforce the support order. The "children" are adults. Some cases hold that the right to enforce a support order for a minor is that of the child once the child reaches their majority. IF your child was disabled with a permanent disability, then the guardian may be able to go forward.
Any determination as to whether too much time has passed will be based upon the particular facts and circumstances. Was an effort made to find the father? If so, was it cursory or was a real effort made? Did the father change his name? Hide? Or, in a place where he could have been found if a dedicated effort was made, such as in the military or in jail? How many times did you attempt to locate him? And so forth.
I hope you found this response to be of assistance.
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