Peter, I know this has languished here with no responses, and I'm sorry for that. I think the reason is that the source data is the cornerstone for everything, and those data seems to be in two or three different places...and the genealogy in a fourth. Makes it extremely difficult for anyone not intimately involved with the effort to understand what's what and chime in. That said, here are a few random--and quite possibly useless; but that's never stopped me before--thoughts. :-)
First, there are a whole boatload of free utilities, with varying degrees of detail and user-friendliness, available to generate the type of phylogenetic tree I believe you're looking at. You may have already chosen and employed one or more to use; if so, my apology for bringing it up. The good ones will almost always be far superior to working with a manual rendering simply because they're generated programatically, so that new data--and there will always be new data--can be included and the output updated without extreme pain and suffering.
One place to look at some of the better known apps is on this page at the ISOGG Wiki. ISOGG titles the page "Phylogeny Programs" and includes a few conversion or data preparation apps that work with what can be pulled from FTDNA projects. While you're there, you may want to check the section "External Links." Some are quite dated, but some of the phylotree apps have been around awhile, too. Might be worth exploring.
Speaking of dated, something that's developed into a vital consideration in just the past few years is the ability to incorporate Y-SNPs from NextGen testing (a la FTDNA's BigY). For the purposes of a deep dive toward an MRCA, STR testing has its foibles. The data are constantly (well, semi-regularly) adjusting our understanding of STR mutation rates, and for any given per-STR, per-generation mutation rate estimation rate I've seen, the accuracy range is only about +/- 15-20%. Not terrible, but still a one-in-five chance that our understanding of the actual frequencies is wrong. Too, I've seen no published mutation rates for about 60 commonly tested Y-STRs (published is key, because I'm certain companies like FTDNA track their own databases to help refine their matching estimates), and of those about a dozen are trinucleotide markers which can be very slow to mutate in some haplogroups, much faster in others...so estimates usually aren't published for those because of the disparities.
Of the Y-STR mutation rates I've seen, two of the slowest are DYS455 and DYS454 at a 0.00016 chance per generation (DYS454 also has the distinction of being the most stable: 96% of the records in Ybase show 11 repeats). The quickest mutator is DYS724, more commonly known as CDY, a palindromic marker that changes at the comparatively astronomical rate of 0.03531 per generation. The result is that you can have one STR marker mutating at a rate over 220 times than another marker...and the whole estimate of genetic distance from STRs is as much art as science. In fact. it's only been about 24 months since FTDNA switched to the "infinite allele" model, significantly liberalizing GD estimates of palindromic, multi-copy markers.
A roundabout way of saying that I think NextGen testing is the future of phylotrees for DNA projects. The data is still coming in at a frenetic pace as more and more men take these tests, but SNP testing has the decided benefits of A) slower mutation rates, and B) a (relatively consistently) hierarchical structure; e.g., if you're R-BY22194 positive, then you'll also be positive for the older BY3332 and the still older ZZ12. This can make hypotheses of MRCA branching more accurate, and can even allow estimates to reach back prior to what we normally consider the genealogy timeframe into clan phylogeography to the period just before surname adoption. Working with the Williams surname ain't the farthest thing removed from Smith, so I can understand how valuable a method might be of being able to sort back to, say, the Battle of Hastings. ;-)
Last up, I remembered that Dr. Maurice Gleeson was on the schedule at the FTDNA annual conference last November...one I had made reservations to attend, but at the last minute could not. But, yep: his presentation is on YouTube! Might be worth the 52 minutes to give it a look: https://www.youtube.com/watch?v=ZyGAid-EgsY (might be worth looking at his YouTube channel, as well, for other stuff; he has a number of vids available). The audio is somewhat off in spots, so you may need to crank the volume a bit.
Good luck with the Smiths!