Hello Everyone!

Is it possible to add a new lead to an existing contact? We sometimes have people who reach out to us for multiple services throughout the year. I don't want the team to create a duplicate contact for someone who is existing. We typically only convert a LEAD to an OPPORTUNITY (DEAL) when we are able to schedule a service appointment. So, is this possible? I have tried to add a lead to an existing contact by using the related list but it doesnt give me the "+" option.  Thank you.