Inductors in Parallel:
Figure: Parallel Inductors
Let the two inductors connected in parallel be L1 and L2, and current flowing in them be i1 and i2 respectively. Let the mutual inductance in among the two be M.
Now, i = i1 + i2
Case 1
Whereas the two fields assist each other, then
L = L1 L2 - M2 / (L1 + L2 - 2M)
Case 2
When the two of the fields oppose each other, then
L = L1 L2 - M2 / L1 + L2 + 2M