1. Nominative plurals and THEY as the subject of the verb

2. The plural of ancilla is ancillae of servus is servi of dux is duces
So subjects can have plurals just like any other case
But

3. The verb must agree with the subject
Ancilla urbem occupat means The slave girl attacks the city. Ancillae urbem occupant means The slave girls attack the city. The verb reflects the fact that the subject is now plural. So

4. The majority of tenses follow the –t to –nt rule
servus tauros agebat and
servi tauros agebant
dux aurum celaverat and
duces aurum celaverant
puer accedebat ut aquam biberet and
pueri accedebant ut aquam biberent
!!But there are some glitches!!

5. Glitch 1. perfect endings –it to -erunt
Filius flumen spectavit
Filii flumen spectaverunt
Dux crimen fecit
Duces crimen fecerunt
Pater corpora tulit
Patres corpora tulerunt

6. Magister verbum docebit. Magistri verbum docebunt. Latro donum mittit.
Glitch 2 –it to –unt In the present and future forms, an –i becomes a –u before -nt
Magister verbum docebit.
Magistri verbum docebunt.
Latro donum mittit.
Latrones donum mittunt.

7. Irregulars use that –unt fert becomes ferunt it becomes eunt
Glitch 2 and ½: Irregulars use -unt
Irregulars use that –unt
fert becomes ferunt
it becomes eunt
vult becomes volunt
potest becomes possunt

8. Glitch 3. –io verbs always show an -i
Magus corpus sepelit. (sepelio)
Magi corpus sepeliunt.
Miles signa rapit. (rapio)
Milites signa rapiunt.

9. And passives? In the present system, just insert that –n-
Urbs occupabatur
Urbes occupabantur
Frater mittitur
Fratres mittuntur
Carmen audietur
Carmina audientur

10. The perfect system plural needs looking at
While the third principle part is used for the active perfect forms
Miles arborem fregit
Milites arborem fregerunt
The passive forms are made from the fourth principle part (the past participle passive) plus a helping verb. And both those forms need to show plural endings.

11. The perfect passive verb needs to agree in
The perfect passive verb needs to agree in gender (m/f/n) and number (s/p)
arbor ab milite fracta est. (arbor is fem.)
arbores ab milite fractae sunt.
dux ab hostibus latus erat. (dux is mas.)
duces ab hostibus lati erant.
carmen ab poeta scriptum est. (carmen
carmina ab poeta scripta sunt. is neu.)