Hello!
You will need to somehow add these markets and refresh them, all three of them for each match where you intend to trade. If you add them manually from the sports tree, then obviously, you will know yourself whether they are available or not, and simply leave out the matches where these markets are not available.
If you are adding them via Market Locator, then add these conditions to your trigger:
and Selection's Trigger Expression football1_s_1_back_price is between 1.01 and 1000
and Selection's Trigger Expression football2_s_1_back_price is between 1.01 and 1000
and Selection's Trigger Expression football8_s_1_back_price is between 1.01 and 1000
This way you are addressing the back price of the first selection in each market. If the market is missing, the condition will always be false.