You can override the main baluster pattern and set a specific pattern for stairs.
- In a plan view, select a railing.
- On the Properties palette, click Edit Type.
- In the Type Properties dialog, for Baluster Placement, click Edit.
- In the Edit Baluster Placement dialog, select Use Baluster Per Tread on Stairs.
- Specify the number of balusters on each tread.
- Specify the baluster family for the stairs.
- Click OK.