1) a) It is only right that she should have a share.
b) It is only right that she have a share.
c) It is only right that she had a share.
d) It is only right that she should have had a share
a & b are the same. b is more formal as it uses the subjunctive. c suggests that she got the share, as does d. It is difficult to give the differtence between the last two, but c is more definite.