Avoiding a conflict isn't healthy in sustaining positive relationships for a few reasons. One, if something bothers you and you don't say anything about it, you'll allow the issue to fester. Eventually, it may come up in the wrong way or at the wrong time. Second, if you always avoid conflict, the other person in the relationship will never know what you're actually thinking, which will lay the foundation for a shaky relationship.
False - there is no subject-verb disagreement as "...my siblings are coming to the party" is correct. It is plural as in "are" because the nearest subject is plural as in "my siblings".
