How to set up child fund "incognito"

Hello: How could I set up an educational fund/trust for my young child who is living with my ex-fiancee (who is married but her current husband does not "who the father is") and to do this confidentially without him having any knowledge? Also where/what avenues should I be looking at for funds/trust?
If this is not information, please let me know. Thanks,Hal
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