2 bottles of 15kg ?
That's is a lot of suppers/teas/coffees and hot showers, how long are you thinking to be on the road? Even if your cooking 3 hot meals a day for a small group of people.
I would start with two fresh bottles and only invest in the regulator (like Noel showed) and maybe some spare/universal connection bits.
You can always buy a local bottle (blue/red) with a matching regulator or just a burner if you don't succeed to find a filling station or a good replacement.
BTW. we (2 persons) used 2 R904 bottles + one refill in 6 months N-W africa, as a backup-unit we took a small burner with extra c206 cartridges.
But I should mention we like every oportunity to let someone else cook.
Refill was no problem in Mauritania although it was a bit scary, imagine a big gaztrailer with a hose coming out of it's belly, a small balance/scale for the right weight and a man happyly helping this tourists with a burning sigaret in his mouth, aah sweet memories...
bart & sophie