hi
I only want the trigger to check maybe 2 markets from within a single football match, not fire against any other matches I am monitoring. 
to link 2 or more markets to 1 match, you should use        market_parent_id
so you would have 2 triggers set to remember
mo_market_parent_id for match odds  with a condition to use the favourite
ou1.5_market_parent_id for the over/under  with a condition to use the favourite
your conditions to link would then be
and mo_market_parent_id_1_back_price is less than x
and ou1.5_market_parent_id_1_back_price is greater than x
if you need more help to setup the triggers please use this link  
http://community.welldonesoft.com/make-me-a-trigger!/then mark or myself will complete the triggers for you
mcbee