Michael,
Its very easy for her to regain Philippine citizenship. If she bought the land before she became a British citizen there are no limits to how much you can own.
If she purchased the land after she became a British citizen there are limits which Fred covered.
There are many former Filipino's who have exceeded the limit and have never had a problem. If it was challenged in court all she would have to do is go to immigration and swear an oath allegiance and she would go back to being a Philippine Citizen. Problem solved![]()