I am a freelancer from upwork and during my 7+ years I worked with one of my USA client. I even used to hire other freelancers for the team. Once he allowed me to pay off one of his freelancer through his login and password. I paid him and after few hours upwork suspended my account that I was using a USA based ID from Pakistan. I explained that I worked as team lead for my client and he allowed me to pay the other freelancer from his credit card.
It took me around 15 days to resolve the issue they investigated it through all the aspects. I involved my client as well and then they reactivated my account with warning that , It was my first and last mistake. If you want to do hiring then ask your client to add in his upwork agency and allows the rights from there.
That was very critical situation I had 5 star profile and years work on their and everything was on risk. So I recommend not to have multi login from same IP. It can create problems for you.
I even heard that fiverr also suspend the accounts from same IP without any prior notice. (No personal experience with fiverr)