一体 => …the heck; …in the world; …on earth N3
合う => do something together N3
~こと請け合い => I guarantee ... N1
Happens next
[合「あ」]う => To do A together/mutually N4
Secondary Verb
~ひょうしに(~拍子に)   => the moment [A], unintentionally / inadvertently caused something to happen N1
場合(は) => in the event of; in the case that ~ N4
[可能系「かのうけい」] => Can, be able to, be possible to N4
Can, Should, Must
~ににあわず (に似合わず ) => ~Different from N1
Evaluate
と伝えていただけませんか => Could you tell, Could you convey N4
ように言う/頼む/注意する/伝える => to convey; to report; to transmit; to communicate; to tell; to impart; to propagate; to teach. N3