If you do the OFHG, the VANOS oil line is right there, which is on the leaks greatest hits list for this engine. I'm pretty sure the top end of it has to be removed when removing the OFH. If that line leaks, now would be a good time to replace it. The oil line has banjo bolts on both ends, both requiring a pair of crush washers.

And I do agree with the other good advice you've got regarding isolating the leak carefully by cleaning and inspecting, and by doing the easier OFHG before touching the oil pan gasket.

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2001 X5 3.0i, 203k miles, AT, owned since 2014