Aside from McNally's promotion, the marketing departments of the two brewers will remain intact.
Guy Shreeves will continue as head of marketing of the Charles Wells brands and George Wright will retain his marketing controller role at Young's.
The brand portfolio created by the union is under review; an announcement of a restructure is expected in August.
Wells and Young's Brewing Company will begin operating on 2 October.
All of the Young's beers will be brewed in Bedford alongside the Charles Wells brands, including Wells Bombardier, Corona and Red Stripe.
The creation of Wells and Young's spells the end of Young's' Ram Brewery in Wandsworth, London, the sale of which is in advanced negotiations.
The united company is 60% owned by Charles Wells and 40% by Young's.