How do you retain or add sweetness to rum?

[welly]

I've made two rums now, one of them quite tasty after ageing for 6 months with oak staves. The other is in a barrel ageing. Also quite tasty but will be much better once it's had some time. One of the commercial rums I have in my booze cabinet and particularly like is a bottle of Pampero Aniversario.

It is fairly sweet to the taste, much more so than my rums. I wondered how you get that sweetness in a rum? Do they back sweeten it with some kind of sugar or is the sugar somehow retained during the distillation process? Or perhaps the ageing in whatever barrels they age it in adds to the sweetness?

Is there something us small scale rum producers can do to add back a bit of sweetness to balance and perhaps enhance the molasses and dark sugar flavours in the rum?