Mr. Jackson, plural Messrs. (or the Messrs.) Jackson.
2. Mrs. has no plural. The name itself takes the plural form. Thus,—
Mrs. Jackson, plural the Mrs. Jacksons.
3. In the case of Miss, sometimes the title is put into the plural, sometimes the name. Thus,—
Miss Jackson, plural the Misses Jackson or the Miss Jacksons.
The latter expression is somewhat informal. Accordingly, it would not be used in a formal invitation or reply, or in addressing a letter.
4. The plural of Master is Masters. The name remains in the singular. Thus,—
Master Jackson, plural the Masters Jackson.
Other titles usually remain in the singular, the name taking the plural form: as,—the two General Follansbys. But when two or more names follow, the title becomes plural: as,—Generals Rolfe and Johnson.
82. Some nouns, on account of their meaning, are seldom or never used in the plural.