In a wikid shareable tree, can I have just three generations ??
The number of generations in the Wikid Shareable Tree is fixed at five.
However, depending on how you want to use it, one of the family tree widgets http://www.wikitree.com/about/family-tree-widgets.html might suit your purposes. Many of those have three generations. Even though they're designed for embedding on web pages, they all have web pages you can link to. For example, substitute one of your IDs in for "Sample-7" in the following: http://www.wikitree.com/treewidget/Sample-7/