What does it mean that Alan's relatives would have to " paper" him and David?

To "paper" means to offer a reward.

Well, follow me out, and ye’ll, I’ll see that I’ll have to get a paper out against ye mysel’; have to offer a reward for ye; ay, will I! It’s a sore thing to do between such near friends; but if I get the dirdum[23] of this dreadful accident, I’ll have to fend for myself, man. Do ye see that?’