Upvote:1
This is a bad idea.
While there is no official rule of X months in a calendar year, she will not just get another six months on return, at best will get let back in to take her flight back in September, and has a very high risk of being refused entry entirely.
Guidance for home office staff says directly (page 11):
There is no specified maximum period which an individual can spend in the UK in any period such as β6 months in 12 monthsβ.
However, when deciding if someone is a 'genuine visitor' as opposed to somebody trying to use visitor status to reside in the UK, they will consider things like (page 10):
the number of visits made over the past 12 months, including the length of stay on each occasion, the time elapsed since the last visit, and if this amounts to the individual spending more time in the UK than in their home country
the purpose of return trips to the visitorβs home country and if this is used only to seek re-entry to the UK