so what if Pam’s Essence was added to lulu?

Although it would make him more lewd and loose, adding Pam would be detrimental to Lucian. Either Pam’s strict sexuality/fixation on men would make Lucian less sexually liberal than Rin would like. Or Pam’s personality would damage Lucian’s; Pam has very low self worth and self esteem (which is why he lets men use him as much as they do as well as offering free sex on the streets), making him nothing but a negative blotch on Lucian’s character. Rin doesn’t want to go through the trouble of raising someone with self-esteem issues, which is why she added a matured personality like Claire to sidestep the issue completely.

Pam meets a guy in 10 minutes and has something in his pussy on the 15th minute.  Everything is usually rushed for his enjoyment and will even try to attract men while he’s doing other things like groceries and the like.  He even offers men to have sex with him free of charge.