* Brothers marrying sisters

[RobertW]

There are two brothers George and Harry in one family and there are two sisters Sarah and Mary in another family. George marries Sarah and Harry marries Mary. I am hoping there might be a query which allows me to search for this occurrence.

[Gowermick]

Offhand, the only way I can think of, is to create a common note explaining the circumstances, then link the note to each of the individuals concerned ,a simple query could then list everyone linked to this note.

PS a similar solution could be applied to twins. Rather than set a “One of Twins” flag (as I have done ), a neater solution would be to create a common note to this effect, and link this note to each individual it applies to.
I say neater, because notes are usually more visible than flags!

[Jane]

As an aside you can detect twins with an expression. how_to:find_twins|> Find and Mark Twins (How To)

one sibling pair marrying another is not that unusual I have a couple in my own tree.

You could query checking each of the relationships for
"wife's sister's husband" and "brother" on the same record.

If you want to scan the whole file you would probably need to write a plugin.
eg For each record, build a list of Wives and Siblings for the record and any wives and then compare the lists looking for married couples between the lists.

[tatewise]

Regarding twins see Twins (6606) that offers expressions for use in Diagrams and Individual Queries to find any twins, triplets, quads, etc.

Regarding siblings marrying siblings, use an Individual Query with a Rows filter Expressions such as:

=IsSameItem(Field(Individual(NextSib(%INDI%,1)),'INDI.FAMS>'),Field(Individual(NextSib(%INDI.~SPOU>%,1)),'INDI.FAMS>'))

=IsSameItem(Field(Individual(PrevSib(%INDI%,1)),'INDI.FAMS>'),Field(Individual(PrevSib(%INDI.~SPOU>%,1)),'INDI.FAMS>'))

=IsSameItem(Field(Individual(PrevSib(%INDI%,1)),'INDI.FAMS>'),Field(Individual(NextSib(%INDI.~SPOU>%,1)),'INDI.FAMS>'))

=IsSameItem(Field(Individual(NextSib(%INDI%,1)),'INDI.FAMS>'),Field(Individual(PrevSib(%INDI.~SPOU>%,1)),'INDI.FAMS>'))

Those cope with adjacent married siblings where the siblings can be in either order.

To cater for siblings who are not adjacent will need more expressions with nested NextSb(,,,) and PrevSib(...) functions such as:

=IsSameItem(Field(Individual(NextSib(NextSib(%INDI%,1),1)),'INDI.FAMS>'),Field(Individual(NextSib(%INDI.~SPOU>%,1)),'INDI.FAMS>'))

but the quantity required grows exponentially, and the problem would be more easily solved with a Plugin.

Once you have found such relationships, whether twins, or sibling marriages, you could add the Individuals to a Named List for future reference.

[DavidNewton]

Just a passing comment: would the second level relationship pull out this information. I have only one similar instance in my tree where a sister and brother married a brother and sister. The second level relationship reads 'Thomas --- is husband of sister of husband of ---'
David
Added in edit. I was thinking in terms of a plugin not a query

[RobertW]

Thanks for the responses. Jane and Mike Tate have helped me to understand the complexity of the issue. Since it occurs quite rarely, and you are almost certainly aware of it when initially entering the data, i think something like Mike Loney's solution would work for me.