Nothing other than the usual requirement, such as returning to UK before the visa expires. She should carry some documents to establsih her UK residence, such as details of accommodation and bank statement for re-entry.A wife will be visiting her parents for 4 months in Pakistan. This is her first trip outside UK after getting her spouse visa in Jan 2010.
1. What are the rules for this?
Yes, provided her main home is in UK. There is no stipulation about how long she can stay away from UK for ILR, but should she want to be naturalised, prolonged absences can disqualify.2. Is she allowed to stay more than 90 days? If she stays more than 90 days, will it affect her in a long run?