Just reposting my earlier findings to compare the two methods.
Because of the way SF does these charts it is not an easy thing to try and compare these two methods, although I think it is necessary. Perhaps they are both equally valid - at least we've already seen some interesting examples of simply doing the SA movement from the start time of the relationship.
If I do the same to my composite as I did with yours, Steve, just moving the angles by primary motion I do see the milestones of those angles to the planets.
This means approximate timings of:
about 8 yrs into our relationship the downer of Saturn was the first real trouble we had in 2015 (we started in March 2007) when suddenly things changed so much after having had our first years of love, connection, making our home renovations, bringing two children into the world and then suddenly me going into a strange period - not wanting to marry him when he asked, but went to the opposite extreme of almost separating at the time. The AC is one degree off a direct hit for that.
If I regress the AC to Venus it is almost 10°, and it was just 3 months short of our 10 yrs anniversary that we got engaged in Tenerife, Christmas 2016.
Not sure what to make of the IC to Mars, that is 9° and we did actually move to Edinburgh when we had been together 9 years, or in summer 2016. But in other ways I am not sure of the Mars energy around that time since it was actually just a time of study... so would fit with regressing the IC to meet Mercury - but that seems too far off strangely since we both went back to Uni, it would have been very descriptive of that year. But this chart seems to give us Mercury influence this year, or 12 yrs into our relationship. This would also mean that next year is REALLY shaky with the IC moving to shattering Pluto which could mean a new start, moving homes or possibly a separation or a separative heavy period. IF the relationship survives that Pluto touch ... then the next touch will be the AC to the Sun in 7 yrs time.
IF I compare and use a slightly earlier bt for myself, but same for his... then the AC is on the direct midpoint between Ven & Sat, meaning approx 8 Degrees from both - which would fit with year 2015 when he actually proposed and wanted to get married and I said no with a period of downfall in the relationship. Very fitting.
The earlier bt would also fit with the regr IC hitting Mercury when we moved to Edinburgh and both studied our first year here ...this would be followed by the IC touching Mars about 11 yrs into the relationship... which is essentially the last year (full of tensions and fighting - our children have never seen this kind of aggression from their father before) ... and this would mean the Pluto separative period would be slightly later or in about 2-3 yrs from now. Let's see if we survive
SF portrays these charts strangely when viewed in a biwheel. But this is what I see if I simply do two solar arc charts for the two individual charts and then put them together into a composite and then I look at the two composite charts in a biwheel.
SA comp Moon is now 1,24°separating orb from square comp Uranus and within 3° from comp ASC (I guess this is maybe too big an orb to show yet).
SA comp Sun is 1,15° from comp Pluto.
SA comp Mars is partile sq comp Saturn.
SA comp Venus is 0,03° square comp Neptune.
SA comp Mer is partile trine comp Moon.
SA comp Saturn is 0,05° conjunct comp IC.
SA comp MC has just moved past the comp Uranus.
SA comp Uranus is partile trine comp Saturn.
And to also note this method of solar arcing our individual charts and then putting them together into one composite for a certain date - this is what was showing up on 24.12.2016 when we got engaged I see that
SA comp Moon partile conj comp IC and partile (0,05°) square comp Jupe which is partile conj comp WP.
SA comp Sun 1,04° separating from square comp ASC.
SA comp Venus partile sextile comp Jup.
SA comp MC 1,14°separating conj comp Venus.
So in my own case those methods both seem to be valid.