Can't get filter conditions to nest

I'm trying to create a filter that does the following:

Show all events with 'xyz' in either EventInfo or ExtraneousInfo, except for NewGroupMember and DeleteGroupMember events. ('xyz' being a security group name)

Whenever I try and drag any of the fields to the conditions box, they just form seperate groups--I can't get any of them to nest together. It either does nothing or the field I'm dragging replaces another field. Help please!

~ Cassandra