In English, the plural is Mullinaxes Other languages make plurals differently.
The plural form of the surname Gillis is Gillises.
The plural of Shastri would be Shastris
If Gelpi is a surname, then the plural is Gelpis.
If Hoix is a surname, then the plural is Hoixes
The plural of the surname may be Simmons or Simmonses.
The plural of the surname Sarli would be Sarlis.
The plural of bràthair (brother) is bràithrean. (This would not be for the surname Brothers.)
A surname cannot be pluralized.
The plural form of the proper noun Justiz is Justizes.
The surname Hester has the plural Hesters (two Hesters, or the Hester family).
According to the Better Business Bureau, Mullinax Ford in Florida does not have any outstanding complaints at this time. In the past 12 months, the Better Business Bureau reports that there have been 3 complaints against Mullinax Ford, all three of which have been closed. Also, the Better Business Bureau reports there are no government actions (significant) involving Mullinax Ford.
The plural form of Hass is Hasses, e.g. All the Hasses were invited to the wedding.