Views: how to make an OR condition between filters and contextual filters

I have been able to separate Views filters into groups and apply an OR condition, following this article: http://www.webomelette.com/drupal-views-filters-and-or-logic

I also understand how to use the hook_views_query_alter() to make a few contextual filters act with an OR statement between each contextual filter.

What I can’t figure out is this: how do I make the conditional between the REGULAR filters and the CONTEXTUAL filters? After altering the query, this is what I’ve able to create:

WHERE 
(
  ( (og_membership_node.gid = '8' ) 
    AND (node.status = '1') 
    AND (node.type IN  ('event')) 
    AND (field_data_field_event_type.field_event_type_tid = '12') 
  )
  AND(
  ( (node.status = '1') 
     AND (node.type IN  ('event')) 
     AND (field_data_field_event_type2.field_event_type_tid IN  ('11', '10')) )
  )
)

and I want it to be:

WHERE 
(
  ( (og_membership_node.gid = '8' ) 
    AND (node.status = '1') 
    AND (node.type IN  ('event')) 
    AND (field_data_field_event_type.field_event_type_tid = '12') 
  )
  OR(
  ( (node.status = '1') 
     AND (node.type IN  ('event')) 
     AND (field_data_field_event_type2.field_event_type_tid IN  ('11', '10')) )
  )
)

To give some background of what I am trying to do: I am using Organic groups, and I want my view to show events, Global, Regional and Chapter events. However, if the event is of type Chapter, I want to only show Chapter events which are in the same group as the page content.

I had manually edited the query to move the regular filters associated with the Chapter filter into the contextual filter group, with this:

foreach($query->where[1]['conditions'] as $condition) {
  $query->where[0]['conditions'][] = $condition;
}
unset($query->where[1]);