1. May I know why is “aunt” referred to as “ibu saudara”, and not “ibu saudari”?
Because saudara refers to fellow brother whereas saudari refers to sister.
Given that aunts are females, wouldn’t it make sense if they were addressed as saudari instead?
That Ibu saudara is the term for aunt implies that it is a man’s world.
The lineage is male oriented & saudari does not have the privilege bestowed on saudara.
Hence it is the common cultural practice to pass down the surname of the father.
2. Does the term “pak” in “pak cik” refer to father?
Pak is an addressing term for male;
Pak cik is a smaller male resembling father’s younger brother.
Hence the term befits an uncle.
Later all the male figures, younger (or older) than father, may be included to a politely extended family.
3. When referring to an uncle who is blood-related, can we refer to him as abang emak or abang bapa?
Abang emak/abang bapa may be used as an explanation to clarify the meaning of bapa saudara.
The term specifies the exact side of the family this uncle belongs to.
Do note that the term is insufficient to cover adik lelaki emak/bapa.
However the term cannot be used to address the person:
Like you won’t use ma ma de ti ti for jui jui in Mandarin; or
Mother’s brother for uncle in English when you are looking right at that relative of yours.
We avoid a longer version when we have the shorter term…(Sew’s Energy Conservation Theory)