"Generally it would be fine for me (/us) what people do in their non-work time, but if it affects our work, then it's not acceptable. So how can we identify suc

"Generally it would be fine for me (/us) what people do in their non-work time, but if it affects our work, then it's not acceptable. So how can we identify such a situation?" I feel like you just answered your own question. If you say you'll be fine with someone working multiple jobs if it doesn't affect their output then why would you need to "identify such a situation"? Just let people do what they want and evaluate people's output and performance.