My American sister who lives in England is coming to the US this week to visit our Mother who is in hospice care. Over the last few years Mom has been gifting to her children. My sister has left her share here in bank accounts in her daughters' names. She plans to take $15k cash back to the UK when she returns. She will carry $7500 and her SO will carry $7500.

Does she have to fill out this form and report it? And if she does, will TSA hassle her about where the money came from? Does she have to answer them? Who does she give the form to? She is American but her SO is British.

Should she spread it around her carryon bag and purse so it won't show up on the x-ray as a block of bills and the TSA will try to impound or steal it?