Biku Le Bruin i heard was initially in Europe before joining JB's Wenge BCBG. Not sure if he was on previous albums before Anti Terro but personally i knew him when he did his first composition with BCBG on the song Plainte A on the album Anti Terro. I believe he's back in Europe, he must have stayed back when a number of BCBG musicians left JB Mpiana mid tour of Europe around 2005/6 or so,maybe he could be in the UK too.
In fusing in young guys in Wenge BCBG, JB was simply responding to fans who wanted the restoration of Pipiyu which consisted of young,talented and energectic musicians at the time when fans started calling the older musicians Ba Mikuli. They used to play first before the main band but eventually got fused into the main band and some of them remain there for instance the singer Nono Fuji.