Would staying longer than declared in Tourist Visa affect a Family Visa application?

[topgim]

Hello,

My partner is visiting me on a tourist visa but may stay over their declared days and stay a month or so, this is still fine as its within the 6 month period of course?

I understand doing this could put a black mark onto their self in the system. In the future we will look to get married and to apply for a family visa so they can live in the uk with me, would staying say 40 days instead of the declared 20 within the tourist visa put a blackmark on themselves and would this then affect a family visa application?

I initially thought not as at that point its to live in the uk rather than just visit so they the government don't have to be afraid of them not leaving.

[yomishu]

I don't think it will have a black mark as long as they go back before the visa expires. I know friends parents who have come down on visit visa and stayed till 6 months - multiple times