Help with ある
I wonder if you could help me with a book (A dictionary of basic Japanese grammar) that I am reading. For ある it says that "When ある is used to express the idea of having and the object is animate, that object must be someone who maintains a very close relationship with the possessor, such as a family member, a relative or a friend. Thus, (4) is acceptable, but (5) is odd.
(4) I have three children.
Whenever I use ある in this way, I am corrected and told to use いる instead which makes sense to me. Even in the いる section of the same book is the sentence 「私には子供が三人いる」.
Do you think the use of ある is just very very rare or maybe it has become outdated since the books publication?
Thank you for your help!