IMO,.. "all" of U,meaning the adults here, need to Drop the issue & move on!It was an accident!
YOUR teen nephew put his hands out to shield himself!"YOU" said it!It happened so fast!!!
.It sounds to me like his sister(age ?) was possibly trying to get HIM in bigger trouble.. and after raising 2 children, BOY& GIRL, & 3 years apart.. it became obvious that siblings can do that ,meaning tattle on the other sibling & just to see what will happen! Maybe your SIL..,was annoyed ,as she viewed the issue,as his sister ,as adding fuel to a fire, ganging up on her brother .. &.. for something he did not mean to do,to your daughter,in the first place ! !If it is no big deal(?) tell your SIL, all is well!. Then you could take the high road & say,..that maybe your daughter should not have been trying to scare him,. as well! Reassure them all that YOU ARE not upset ,this is a misunderstanding & leave it at that!Calling your nephew a liar??..well... IN a car accident 14 people will see it 14 diff. ways ,& that is part of the issue! ..I am sure your nephew felt badly over the ACCIDENT..(and his cousin's bloody lip) ..IT does not sound like he ever ment to hurt her (he just overreacted) ..& in his mind (instant replay)he never touched her..But her lip ran into his hand/ ,when she was Scaring/ Pranking him!I think your MIL should totally stay out of it all! Period! MOVE ON!:)IMHO,.YOU & your SIL. could be making a "monkey" out of a mole hill!So maybe U could buy a funny "monkeyface mask" & tell your SIL ,she has permission ,to put it on & come over & scare you,too!;-)
Why was your daughter trying to scare her 14 year old cousin?Sounds like she likes getting his attention!! LOL. Also Sounds to me like she did a "lip licking".. good job of scaring him.. ! LOL..