Already covered here but i'd like to give it another nudge https://centrecrm.uservoice.com/forums/249581-general/suggestions/6639944-make-client-contact-addition-easier

The current process is really counter-intuitive. At a minimum could we perhaps have a pop-up warning when adding a new contact/client that it perhaps needs something attaching to it? A 'would you like to attach a contact to this client' box perhaps? It's a real bug bear as it stands, i'm constantly adding clients, creating jobs then realising there's no contact attached.