Can someone please explain to me how the Skywards family account works with credit cards?

My girlfriend recently transferred Amex points to Skywards, then joined my newly created family account with 100% contribution.
Unfortunately, the miles were not available and the agent told me that this was because she had joined the family account after transferring the points.
In order to redeem the miles, the agent therefore advised her to set the contribution to 0%, transfer additional miles from her credit card and then redeem them through her personal account.

Her Amex account only has about 20k miles left, so I'd like to use them up by transferring them to the family account, then top up from my own credit card afterwards for a redemption.
Will that work? According to the callcenter agent, it should, but agents are often misinformed.
Will it work with credit card points, too, or only with points earned from flying?
If you leave a family account, will you get the miles back into your personal account?