Sharing an account can be tricky, there have been issues in the past when a rogue employee logged in and and claimed to be one of 2 people, since the posting originates from the same IP address and possibly same computer/device it is hard to know who is who, saying what. For the sake of clear communication I would advise against it, however Spark will have the last say in the matter.
A while back, we had a supporting dealer that was selling knives, he started posting in a completely different and unprofessional manner, his posts were riddled with broken sentences and phrases laced with profanity etc. When confronted, he said it was his business partner and not him. He further stated he was having issues and his business parter became indebted to someone and needed to sell high dollar knives to make the money back, etc. It was a story that you might find in a B movie script garbage can. He was given the benefit of the doubt once and it continued. We grew tired of that BS and he was banned permanently. He then laced his facebook page with insults towards us, badmouthing the owner and the mods for banning him, etc.
So, you can see the dilemma one might face with more than one person using the same account.