Adding more spheres to an object in ZBrush can greatly enhance your sculpting capabilities and allow for more intricate and detailed 3D modeling. Here's a simple step-by-step guide on how to accomplish this:

1. Open your 3D object in ZBrush and select the 'Tool' palette from the top menu.

2. Click on the 'Subtool' menu and select the 'Append' button. This will allow you to add a new sphere to your existing object.

3. A new sphere will now appear in your scene, and you can use the Move, Scale, and Rotate tools to position it exactly where you want it on your object.

4. To further customize the sphere, you can go back to the 'Tool' palette and use the various sculpting brushes and techniques to blend it seamlessly with the rest of your object.

5. Repeat these steps to add as many spheres as you need to your object, each time appending a new sphere and then sculpting and positioning it to your liking.

By adding more spheres to your object, you can create complex and organic shapes with ease, and take your 3D modeling to the next level. Experiment with different sizes and placements of spheres to achieve the desired effect for your project.

In addition, ZBrush offers a wide range of tools and features that can help you further refine and detail your object, such as DynaMesh, ZRemesher, and various masking and sculpting options. Take advantage of these tools to fully realize your creative vision.

As you become more familiar with the process of adding spheres and refining your objects in ZBrush, you will unlock new possibilities for your 3D modeling projects and be able to create stunning and intricate designs.

In conclusion, adding more spheres to an object in ZBrush is a simple but powerful technique that can enhance your sculpting capabilities and give you greater creative freedom in your 3D modeling projects. With practice and experimentation, you can master this technique and take your sculpting skills to new heights.