D&D character with multiple personalities

[Master Chr Smith]

Well if one of those many "personalities" had control long enough, Multiclassing,

(if the DM was kind, it would not stack towards your limit (as they are in effect different people, and as long as you had no control as to who showed up (not in any way controllable) that would be weird but fair)

Might consider treating as non standard cross class (+10% xp/lvl to advance) to make up for the levels of the 'sleeping' personas. Particularly if you have more than one additional personality.