In Occult cleft of upper lip,  the Cleft area is clearly shows groove on contracting orbicularis oris muscle. This is treated as usual cleft lip with proper muscle repair. 

Sub-mucous cleft of palate may also be termed as occult cleft of palate. This also treated as usual cleft palate if there is speech defect.

in cleft palate in age below 6 yr it require treatment as it cause speach defect

Occult cleft of lip (forme fruste) can be treated depending on the deficiency. Muscle defect may or may no be there. Your treatment choice depends on that. vermillion notch can be treated by simple z-plasty or white roll mismatch can be treated sometimes just by taking out a diamond and suturing as a straightline. I do

Overt submucous cleft is when you can see evidence of the cleft on the oral surface. Occult (meaning hidden) submucous cleft is when you can only see evidence of the defect on the nasal surface through nasopharyngoscopy. There may be many individuals who have an occult submucous cleft that is never identified because it is not symptomatic. Occasionally, we see patients with VPI following adenoidectomy, and through nasopharyngoscopy, we find that the cause was an occult submucous cleft.

Regarding treatment, this is only necessary if the individual has evidence of VPI (hypernasality and/or nasal emission) and the patient is interested in having that corrected.

If it is not symptomatic, you don't need to treat it at all. If it is causing hypernasality and/or nasal emission and the patient wants correction, you could consider a Furlow palatoplasty or just go on to do a pharyngeal flap.