First and foremost, my sincerest sympathies for your loss.
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To continue where MeteorWayne (so correctly) left off - there really is no "middle star in ...". You would need to know its actual star catalog designation. Typically something like a Hipparcos, Tycho, or USNO number. Even then, there's certainly no guarantee the star "designated" would be visible to the naked eye, or even to the deepest reaching telescopes.
The way these scams tend to work, unfortunately, is you take a star catalog - let's say the Hipparcos catalog. Inbetwixt 25 Lyn and 28 Lyn there's a star that has designation 71148 in the Hipparcos catalog. I print out that page, I scribble out "71148" with a crayon, and I write in the name you purchased in a handsome complimentary color crayon. I put it in a binder, then print out a fancy looking certificate and mail it to you.
No one else anywhere in the world will recognize it by the name I've given it. It exists only in the binder propping up the wobbly leg on my desk, and on the certificate I mailed to you. You and I have just agreed to call it by some other name - but no one else has. Heck, half the time we argue about which star catalog we're going to use, so we end-up using all of them (the major ones anyway...).
I apologize for being a downer. But that's the reality of it.
My advice? Pick a star that strikes a chord with you, one that you can easily find in the night sky during the season of your son's birth date. Bring your family and close friends outside with a green laser pointer and point it out to them. Dedicate that star to your son's memory. Spending the money on a green laser pointer and a star chart will return a lifetime of learning and observing enjoyment for you and your family and friends. Far more than a certificate printed on a scammer's $30 office supply store printer.
If you need help correctly identifying the star that you ultimately pick, I'd be more than happy to help you there, providing images of plates, and then adding correct labels to the plates and describing how you can "walk" to it from other well known constellations that will help you point it out to family and friends. I suspect I'm not alone in that willingness.