This is a good example of letting someone else think they have a good idea, while all along it was your idea. Like in My Big Fat Greek Wedding- the mom says the dad may be the head of the family, but she is the neck and can turn the head any way she wants to.
If you need something done but need the help of someone else, try getting the person to come up with the idea that you want. If they think of the idea themselves (with a little prompting) they will be all for the idea when they might otherwise object.
It's a tricky business, but it can be effective.
I suppose it is a form of manipulation, but I don't think someone would come up with an idea they were truly opposed to and follow through with it. But gently prodding someone towards a good path for them can help them and others.