Conditional Sentences in English 7
Summary: A look at other expressions with 'if'
6. Other expression with IF
ONLY IF: Teachers may detain students after school only if they have given parents 24 hours’ notice in writing of the detention
Only if stresses the exclusivity of the condition - if the condition is not fulfilled, the situation in the main clause is expressly excluded. Omission of only merely implies the exclusion
IF ONLY: If only I had known that Jill had had cancer [I wouldn’t joked about her appearance].
If only makes hypothetical and counterfactual conditionals expressing surprise or regret stronger. The main clause consequence is often omitted, its message being implied.
EVEN IF: Even if Pompey win all their remaining matches, they can’t escape relegation.
Even if is used when the condition has no effect on the subsequent clause; in  the relegation will occur whether or not Pompey win all their remaining matches.
Certain warnings/threats with and and not ….or convey a message very similar in meaning to conditional utterances, though they are not conditional constructions: The first of the following is a conditional warning; the other two are not.
If you come home so late home again, I’ll ground you for a month.
Come home so late home again and I’ll ground you for a month.
Don’t come home so late home again or I’ll ground you for a month.