[phenixbb] Which is the better way to combine the dataset from different crystals?

Hi all, I have a question on how to combine two dataset from different crystal of the same protein. The first way I could think of is that, 1) Merge two dataset seperately; 2) Scale them to see whether they are consistent with each other enough as indicated by the R-factor; 3) If the R is low enough, say below 10 or 15%, then take the average for both the F and SIGF. The other way is that, 1) Take the unmerged file from MOSFLM, and reset their batch number; 2) Run SCALA to scale these two unmerged dataset at the same time. Could anyone tell which way is the better or the correct way? Thank you in advance! Alphar