Charging 2 x 2s

[mattr]

I know you can safely charge a pair of 2s packs as a virtual 4s, if the charger has enough grunt. Mine does.
Rather than making my own harness to connect the two (and provide balancing as well) does anyone make one?
I've had a look round but don't seem to be able to find anything that'll do the job. Not sure if it's my sub standard Google-fu, or if I'm just looking for hens teeth......