I'm unconvinced that the retro-fit bolt in brace can provide the additional rigidity to avoid this type of cracking at the wishbone brackets.
I can confirm that the bolt in brace will not stop the cracking/fracturing of the chassis. My 2013 car had the bolt in brace fitted Oct 2015 but fractured April 2017. It took 3 months for MMC to return it round with a new chassis. I got them to fit the Centa compensator and check the clutch at the same time. I just paid the parts cost of the Centa. I believe RedThree had one of his new chassis turned round in 3 weeks. The Centa may have caused a delay if parts were not available but if you have early HD type at least ask.
Very disturbing news for many I suspect....
A Morgan Identified Fastidious Owner... 2011 4/4 Bespoke, 1981 Delorean, Auburn Boat Tail