Se eles fossem capazes de saber... - Tradução em inglês

Original sentence:

"Se eles fossem capazes de saber quando e onde voltariam a se encontrar, a despedida seria menos dolorosa."

Suggestions for translation:

"If they knew where and when they would see each other again, the farewell would be less painful."
"If they were able to know where and when they would see each other again, the farewell would be less painful."

Cheers!

Another option. I like the "could-would" sequencing for this kind of statement:

If they could have known where and when..., the farewell would have been less painful.

The time-frame sequencing works this way:

If I could, I would.
If I can, I will.