David comes up with the scam later this month, as Alicia wants to make sure that young Jacob will live with him rather than his dad Justin when she is sent to jail.
Alicia quickly agrees to the idea, but is conflicted as she continues to harbour genuine feelings for David.
Wolfenden told All About Soap: "It happens when they're sat together drinking wine one evening. Alicia's broken down in tears, talking about how Jacob is going to have to live with his father and his new stepmum, who he hates. Then she says it's unfair that, just because Justin's married, it's taken for granted he can provide a better home for Jacob.
"Something is triggered in David's head, so that's when he decides in a bit of a drunken stupor to say, 'Why don't we get married then?'"
He continued: "[Alicia's] shocked, mostly because she's actually totally in love with David and he, as dopey as he is, is completely blind to it and doesn't see this gorgeous girl has fallen for him. He just sees her as his mate and the truth is, he's not proposing for Alicia - he's doing it to keep custody of the little lad."
Wolfenden added that Justin later backs down in the custody wrangle. However, Alicia fails to share this crucial piece of information with David as she still wants to marry him.
He confirmed: "There's an extra twist because Alicia finds out David could have custody of Jacob anyway, because Justin backs down, but she still goes ahead and marries him regardless. That all comes out, as does the fact she loves him - it's all going to be revealed!"
Natalie Anderson, who plays Alicia, will soon leave screens temporarily as she has gone on maternity leave.