Knowing that Mr. Gold was really Rumple and that his baby trafficking tendencies had carried over to his cursed identity, the Home Office/Darling boys might have sent him an anonymous tip that they had a baby if anyone in town would like to adopt a baby for profit. It just so happens that Regina was unable to conceive her own baby due to the curse, and so she approached Mr. Gold around the same time, knowing his inability to refuse a deal. Regina offered to pay him, and in return, Mr. Gold would procure her a child. Having gotten an anonymous outside tip, Mr. Gold unwittingly acted as an intermediary between the HO and Regina.
Sounds perfect to me. THO manipulated everything behind the scenes to ensure all this would work out. Was there anything outside of their control?
For example, Owen and Kurt needed to be in the woods right when the Curse hit in order for Regina to meet them and want to have a child someday. So did they somehow engineer that? Did they murder Owen’s mom? (I know this is going cracky but I thought I’d put it out there)