When BEK was released at least a percentage of the singers had already left before the album was released. For example Rolly Mayemba, Bapinces, Zoe Bella all left after Zenith in 2007, and other singers like Scottie Pippen, DVD Musica left along to join Montana’s group after he himself had just left and none of them were credited on the album booklet .
My question is Koffi usually deletes vocals for singers who have left but for these guys he didn’t especially Rolly who left whilst they were still recording the album and he still had three vocals left on the album, whereas other singers like Asso, Babia etc didn’t have the opportunity to have vocals the same with Montana and Shella who both ended up leaving.

Maybe because he already made the plan of promoting Cindy le Coeur and not male singers anymore, so deleting vocals would not having sense anymore. However, I still believe that he deleted some vocals, because the transition from Jitrois vocal to that of Bapinces sounds not natural. The same for the transition of Joss Diena's vocal to that of DVD Musica. It could also be that Koffi decided to save the vocals of Rolly, Zoe Bella, Bapicnes and DVD because of the remaining singers not being able to do better in the studio.

Another theory is that Koff probably knew that he would soon use Zoe Bella, Rolly and Bapinces in the future for Europe-concerts, which also happened at Zenith 2009.Because in 2007, he made used Junior Kingombe, Mirage Supersonic, Jipson Butukondolo, etc. for different concerts in did in Paris, Brussels, Germany and Switserland. Sometimes I wonder why Koffi just didn't use Europe-based musicians along with Binda Bass  for the missed € 1000 event at Theatre de Gymanse Marie Bel  in December 2008, when he got the visa's for Quartier Latin rejected, that was meant to present B.E.K.

I’m pretty sure he deleted Deplick’s vocal from Bomengo which he brought with him to Maison Mere in Héritiers song Sol de mi amor in Temps Présent, and he also sang Rolly’s vocal from Ikea. Rolly and Bapinces didn’t return after they left they only came back nearly 15 years later, Zoe was the only one that Koffi used for Zenith 2009. 

I understand why Koffi didn’t delete their vocals in Bomengo because they were already singing Bomengo in nearly all their concerts from 2006 to 2007 before the release of BEK, but as for the rest in bb goût Koffi could’ve erased the vocals of Rolly, Bapinces and Zoe Bella and replaced it with Jitrois, Gabbana and someone else because they only had one vocal in the album but I understand it was probably 12.

i think its also because of the pressure to release same thing happened with balle de match with some musicians who have had their work erased either for leaving or for a last minute change of plans and then  some who were not even there anymore saw their work stay i remember koffi was in hurry from the moment some songs started leaking

Deplick already left before the started to recordings of BEK. I don't believe that the vocals Rolly did are of him. I think that he just took those vocals to get accepted them accepted in Temps Present. He did for example Gessac cri as a vocal in Heritier's song Sol de Mi Amor, mixing it with the vocal he was meant to put in Bomengo.