Family of a Chief
Eldest Son and Heir Apparent of a Chief
He is known by his father's territorial designation, with the addition of 'younger' abbreviated to 'yr' (so that it will not be mistaken for a surname), which may either follow the surname (eg Ranald Macdonald, yr of Castleton), but is more usually placed after the territorial designation (eg Ranald Macdonald of Castleton, yr).
Wife of the Eldest Son and Heir of a Chief
The wife of the eldest son and heir of a Chief is known by her husband's style, ie with 'yr', but without his forename (eg Mrs MacGregor of MacGregor, yr), unless she is sufficiently distinguished from her mother-in-law (eg Lady Mary MacGregor of MacGregor).
Younger Sons of a Chief
They are not known by their father's territorial designation unless they are recognised as lairds in their own right, eg the younger sons of Sir Malcolm Innes of Edingight are Colin Innes of Kinnairdy, and Michael Innes of Crommey, being lairds of those old family estates.
Daughters of a Chief
The eldest unmarried daughter of a Chief uses the territorial designation of her House without her forename, eg Miss MacLeod of Glendale, unless a senior lady is still living - when she will use her forename as well as the territorial designation (eg Miss Janet MacLeod of Glendale).
This latter style is also used by all younger unmarried daughters.