Translation:I do not know if they have thought of it already.
In Italian you can use "pensare di" or "pensare a" both means "to think about"
pensare a qualcosa = pensarci:
- to keep someone/something in mind, to remember something/someone, to care for sth., to think of sth./so., to think about (memory)
Penso a mia madre che è malata. (to think about = to keep in mind)
pensare di fare qualcosa/pensare di qualcosa = pensarne:
- to plan , to intend, to jugde, to think of, to think about (opinion)
Penso di andare in Francia domani = I plan to go to France tomorrow. Penso male di te = I think badly of you Che cosa pensi del viaggio? (what do you think about = what's your opinion)
"ne penso" is more often used in questions (to ask someone's opinion) Che ne pensi? Che cosa ne pensa lui?
pensare qualcosa = pensarlo:
- to think that
Penso che la festa era bella. Lo penso pure io. Chi pensa che la festa era bella? Lo penso io.
In this sentence I would use "ci" I think mainly because of the use of "se". [it asks more for the "think about" memory than for the "think about" opinion