Why not use a lighting umbrella, straight into a light stand - made for each other. Random picture from Google… [![enter image description here][1]][1] The lighting clamps generally come with adaptors &/or inserts so they'll fit a mic stand thread [either size], or otherwise they'll just drop right over the end of a standard mic stand & clamp to the straight rod underneath. **…or… gaffa tape.** [1]: https://i.sstatic.net/1CpZQ.jpg