I think you are you are speaking to web Domain Forwarding? So, let's say i punch in 'bob.com' to Google I will land on the home page of a site called 'mel.com'. There on the Homepage of 'mel.com' I see three links to 'Mel.com' the business, 'bob' the business (no longer a .com) and let's 'pat' the business (no longer pat.com). Likewise, if I punch in 'Pat.com' I will land on the homepage of 'Mel.com' and see the three options?
I don't know how mature your business areas are, length of time the sites are live etc. There are other options. For example, you can forward your domain to a social media account of the same name, such as a Facebook page. (I'm unsure if a domain with SQS enables this). I believe if you have a Google Business page, Google now offers a limited web page to be associated with their Business Page if the name is the same. There are a few other ways to go once you own a domain name.
That said, the best option (again depending on your domain/business names, social media accounts etc. ) is to identify those similar businesses as you've done above and roll them into one website with specific landing pages and links to the other business area pages, but do so under a single domain name. The site will have one domain and you start treating the other areas of business at a brand level which is more than a good thing (so mel.com\bobevent2020). No domain forwarding or redirects.
My first question would be: How much existing advertising collateral have you out in the world associated with each website, and how much traffic do they each drive? If you want to save the cost, I'd suggest simply emailing existing customers and inform them that you are consolidating websites and set up the pages under one domain name. It works. You may loose a couple along the way, but they'll find you.
There are many SEO considerations for re-directs and forwarding and most will create problems for you unless your domains are substitute domain names for your brand which is common in retail. For example, if you punch in 'mac.com' you will go to the 'apple.com' website. Larger companies spent years sending (not saying Apple did!) out legal letters to stop companies trading under .com names that they knew were similar or substitutes for their own brands. (i know as I received a couple of letters.) My point being that unless your other domain names are used regularly as direct substitutes for your main website name then put them aside and build the business from a page on a single site and when things start to grow look at the possibility of using these other domains.
My starting point for SEO is always to look at the NAP information as this is how Google etc. looks at your business first before you started putting in the connectors to Social Accounts and Ads etc. - Take your Name Address and Phone Number (NAP) and start searching these to see what returns and in which directories your businesses return. Then look to the Google Business Page etc. From there look at your current sites: Google categorizes all your offerings as 'events', Facebook likewise 'events', so you actually benefit from a single website with the event calendars moving though Google Business Page and Facebook Event pages etc. and you can change and update the landing pages for these events accordingly. The hardest question is which domain do you use? but, use a single domain.
I hope the above is helpful. I don't know the extent and history of your work, or how the sites are plugged into the net. I wish you the best with your decision and am happy to answer any further questions in the forum
Be well! - John