You can think of people as a collective type, though they may do many annoying things jointly or separately. Examples:
My neighbours are a real nuisance.
In-laws are usually a real trial.
"Trial" is admittedly difficult. "Trial" can mean "one incident that is a test of one's power of endurance or forbearance" - in which case we often use the plural "trials and tribulations" (of marriage for example). It can also mean "a situation", in which case we can say "marriage is a trial". "Children" collectively can constitute a "situation"; for example, "My children are a wonderful blessing to me." "My brothers and I are a real trial to my parents." "His step-children are a great torture to him." "Her daughters were a great comfort to her during her long battle against cancer."