“…so if I convert the curve to a mesh and then disable or delete the subdiv…”
To be clear; you don’t need to Convert the Curve to Mesh, it was just used to guide the ‘wire’ Mesh.
Delete the Subdiv Modifiers (don’t disable them).
Converting the Meshes to Mesh, is a trick to Apply all Modifiers at once (that’s why the Subdivs had to be Deleted first).
When You Join the Objects with CTRL+J, all Objects get the same Modifiers as the last Selected one, that is why you had to Apply all Modifiers before Joining.
It’s a bit confusing when you’re just beginning, but if you persevere, ‘all the pieces will fall into place’.
Good luck on your 3D journey🍀
