i just used the barrel for cooling down the beer after the 2 weeks of fermentation before adding them to the bottles. and i just added the extra sugar in there rather than straight to the bottles cause i was afraid
High abv beers that are aged for several months like a barleywine can benefit from adding some fresh yeast at bottling. Some people do this by default. I have been lucky using only sugar to carbonate the boozy beers, but I donít age them for very long before bottling and let them age in the bottle.