Café-grammar. Comitative case.

If you want to order coffee with sugar or tea with lemon then you have to use the comitative case. 
To form the comitative case you need to add the marker -ga to the genitive form. 

Comitative case: with what? 
Komitatiiv. Millega? 

Nominative:       suhkur              koor             sidrun            
Genitive:              suhkru              koore           sidruni            

 Comitative:        suhkruga         koorega     sidruniga         

Kohv suhkruga. - Coffee with sugar. 
Kohv koorega. - Coffee with cream.
Tee sidruniga.Tea with lemon.

NB! Kohv koorega. = Kohv koos koorega
NB! Kohv koorega ja suhkruga. = Kohv koore ja suhkruga.