Perpendicular shear wall footing

Good day,

How can I best model a footing that support perpendicular shear walls. In these cases the footing would intersect each other and would therefore share one common node. I have tried the GEN FIXED command with no errors but with the following warning :

**WARNING, 1 or more joints are in multiple SUPPORT commands, First Joint 2
The subsequent entries will add to support direction specs. See Tech Ref Manual.

Does this mean my final result will be affected and if so how can I rectify this issue. I have attached the STAAD file as a reference for the problem. 

Thanks1663.wall example GEN Fixed.zip