Some Considerations: Reflexive Possessives and Scope (and Lexical Effects)

Consider reflexive possessive pronouns. These exist in Scandinavian and Slavic languages, and very probably elsewhere as well. English does not have them, c.f.

a man₁ should teach his₁ son a trade.
John₁ bought his₂ car yesterday.
John₁ bought his₁ car yesterday.

However, in English, intonation can differentiate the two, and addition of 'own' also serves to disambiguate. However, some languages have separate words:

En man borde lära sin son ett yrke.
John köpte hans bil igår.
John köpte sin bil igår.

However, in Swedish, sin is restricted to non-subjects. You cannot say

Erik och sin fru for iväg till Amerika igår.
Erik and rflx's wife went away to America yesterday.
Erik and his wife left for America yesterday.

And scope prevents you from saying something like

*Hilma hoppas att sitt hus ska stiga i värde.
Hilma hopes  that rflx's house shall rise in value.
Hilma hopes that her house shall rise in value.

Instead, the regular possessive is used:

Hilma hoppas att hennes hus ska stiga i värde. Erik och hans fru for iväg till Amerika igår.

An idea that struck me is that maybe certain nouns in a language with restrictions such as those in Swedish still might have some laxity permitted for some noun-pairs? Husband and wife, parent and child, friend and friend, and various other social pairs, especially? Maybe such noun pairs even transcend the subclause boundary showcased above?

Or maybe there is a hierarchy, where some nouns even can possess from subordinate positions in the clause - i.e. if parents were higher than children in this hierarchy:

rflx's children honour the father
his₁ children honour the father₁ 

This would be highly bizarre in Swedish, but could be cool in a conlang.