It'd be nice to say they are entitled, but they ain't. For the sake of friendship, the winners could give them an amount anyway, though.
Reminds me of one instance though, where a syndicate won but the person in charge of the syndicate claimed to have forgotten to put the tickets on before the draw, then ran off with the £15m.
Lottery Syndicates are, in my opinion, generally just a bad idea anyway. You're relying on everyone being fair and equal, but it's common that (a group of people)+(loadsadosh)=greed - pure and simple. Sad to say, but it is. 🙁