...if you are rigging each individual toe than the toe groups need to have a row of polys between each toe belonging to the foot actor. Otherwise there will be mesh breaks because Poser is confused by child actor having more than one parent. Each child (a toe) can only have one parent, the foot. Hence the row of polygons that separates the children and belongs to the parent foot.

Be careful with how you name your groups. Try to name left and right with lower case l and r and try to avoid punctuation and spaces. Using spaces may cause Poser to regroup. So rToe1 would be ok. Right toe 1 probably not. Obviously this is internal names. External names can be anything you wish. Alot of this is ancient Poser stuff but is still relevant and is standard practice.

Otherwise if it's just having poly selection difficulty you might try grouping it externally in a more precise modeling software. If you are using the grouping tool and selecting in wireframe display it will generally select polys that are facing away from the camera on the mesh too.