When I write dialogue, it's always with the question "what would this character say in this situation?" in my head. I can't force dialogue to go in a direction that it doesn't naturally go in, because that would mean one of my characters is saying something out of character.
I don't write a plot/outline, and the idea in my head of where the story is going is very flexible, so I'd be inclined to adapt the plot to follow on naturally from the conversation (i.e. the one that the characters would have) rather than force a conversation to go in a particular direction to fit the plot. This is one of the reasons why I don't bother with writing a plot/outline, because when I start writing the story, issues like this - characters staying in character and the story unfolding naturally - means that I frequently have to make changes in the next part of the story. Keeping a vague and flexible idea of the plot in my head works. Writing an outline would be a waste of time for me because I'd be constantly changing it.
Note: there are many different ways to write a story and outlines work for many writers, and someone who uses an outline may have a different way to solve this issue. But I think you should consider whether the reason it sounds forced/not meant to be, is because the characters are not in character, and consider whether you need to adapt the next bit of the plot rather than keep on trying to force a conversation that doesn't sound right.