The challenge here is not the translation of the single terms "if," "and," and "when." The challenge is rather how to build a parallel phrase that reads like natural Arabic.

Constructions like "if and when," "any and all," "over and above," "above and beyond," "between and betwixt," "never ever," "really and truly," "aiding and abetting" are common in English. They serve to stress a point by repetition without seeming to be repetitive. Each expression is essentially a one-two punch, a left hand followed by a right hand to hopefully cause a KO. Just like in boxing, a double serving of the same message, delivered with symmetry and in rapid succession, is thought to ensure or at least enhance the effectiveness of the message.

For the translator, a problem will arise when no equivalent expression exists in the target language. Arabic has a few double-dose expressions, such as:

لعل وعسى، دائماً وأبداً

Unfortunately, "if and when" is not one of them. So how do we proceed?

Keeping in mind that there is nothing specifically sacred about the construction itself and that no two languages express every point the same way, a translator should feel at liberty to express not what was said but what was meant.

In this case, the optimal choice in my opinion is to deliver the message in one punch, not two. Any of the following should work:

في حين، في حال، عندما، حينما، حالما، متى ما

They all mean "in the event that....," which should be perfectly sufficient.

If, on the other hand, you feel obliged to be faithful to the source phrasing, especially if you think that the phrasing might have a legal import, then you should make sure to choose words of similar form and function function so that the conjunction "and" serves to conjoin two parallels. Examples:

حالما وحينما
في حال وفي حين
إن حصل ومتى ما حصل أن

The symmetrical construction will ring with less dissonance than a mix-and-match phrase.