Please help spouse visa or other route

Hi I’m new to this forum. Wondering if someone could help me out. I know someone who’s been in this country since 2004 she came on a visit visa aged 14 and overstayed ever since. She has not worked or didn’t go to school but can speak fluent English as she did go to some language classes. She has met a British citizen and they are planning to get married within the uk- religious wedding. What is the best route for her? Is it better to go back to her country and come on a spouse visa (but wouldn’t she be banned for a year I think) or somehow stay in this country and apply for a different visa. I’m a bit confused any help would be much appreciated. Thanks.

Just forget to add she came with 5 other siblings who have now settled through marriage and other and human rights case I believe. So she she has not got anyone back home everyone is settled in the uk.

Hi I’m new here need some advice. I wrote before but no one replied . Basically I know a person who came into this country on a visit visa she was 14 when she came around 2004 she has overstayed ever since. She came with a 5 other siblings they have all overstayed And married British citizens. She is now 27 I believe and has met someone who is a British citizen. Now my question is what is the best route for her to be legalised. I know her siblings got discretionary leave which is along process and is not always guaranteed. A lot of people say if she returns to her country then her partner can apply for spouse visa and that is a better option. My question is if she returns home would they ban her??? Considering she was only a child when she came here and overstayed. And how long before She can come back and how long will the spouse visa take to process. Any help will be much appreciated.