This NOT new rule it indeed old rules. niece or nephew is consider as direct relatives but sister in law is falls under indirect relatives of yours as she is the sister of your wife.
@sms09...you are correct.! anyhow you can still extend her visa of 1 month provided air ticket to the immigration officer, without ticket then sorry to say...no EXTENSION..
Note: if u r kabayan...then PM me..i will tell u best solution for that.

ano po gawin para ma approve ulit another extension for grandchildren?