Measuring length of two wires inside copper with a TDR
There is capacitance from each of the smaller conductors to the larger conductor, so there might be an effective capacitance between the smaller conductors equal to one-half of their capacitance to the larger conductor.
Of course, that does not imply that the capacitance to the larger conductor has no effect. Your statement that the larger conductor &quot;has current going through it&quot; is not enough information to judge how any signal on the larger conductor would influence the smaller conductors.