Can anyone help me with this please?

A BIBD has blocks as given below and some missing blocks but we know that we have all the blocks containing point 3.

By finding the frequency of each point and each pair of points in the known blocks complete this BIBD.

A partial list of Blocks

1234 1258 1356 1378 2368 2357 2478 3458 3467 5678

I have come up with the following missing blocks:

1245 1256 1467 4678.

It's abit complicated to explain how I did so. But I definately didn't pluck them out of nowhere.

Thank you for your help. Much appreciated.