my Wife ILR validity

Dear All,

Currently, both I and my daughter received OCI cards recently and my wife is holding ILR from 2012.
Currently, we are planning to relocate to India from 2017 Summar for a foreseeable period of time.
My wife ILR is valid until 2022 ( usually ILR card is valid for 10 years) and not planning to apply for a British passport for my wife in near future.

My query-

What should we do to keep my wife ILR is valid?
I have been told that my wife has to visit UK for every 2 years ( like a very short trip like one week or so)
I am wondering- does anyone have any clue about my situation or anyone already in the same situation

Please share your thoughts and response would be appreciated

Kind Regards

ILR is lost after 2 years of absence and short visits to the UK do not maintain this.