No, they cannot.
The Esperanto words for grandparents and grandchildren are geavoj and genepoj.
Generally only legally adopted children become heirs-at-law. Since you use the term "step-grandchildren" I assume they were not legally adopted by their step-parent and would not be heirs-at-law of the step-parent's parents. You can check the laws of intestacy for your state at the related question link provided below.
Love your grandchildren.
Because the child's parents parents are called grandparents.
Grandparents can effectively handle unruly grandchildren by setting clear boundaries, being consistent with discipline, and showing love and understanding. It is important for grandparents to communicate openly with their grandchildren and establish a positive and respectful relationship.
Benign means not harmful. So for example, grandparents see their grandchildren as benign lovable children.
No. they do not.
buy them expensive gifts
Grandchildren is already the plural form of grandchild.
Your ancestry. Those you have descended from are your ancestors. My lineage includes my parents, grandparents, great-grandparents, etc., in my past, and my children, grandchildren, great-grandchildren, etc. in my future.
Their own grand grand children...
Your ancestry. Those you have descended from are your ancestors. My lineage includes my parents, grandparents, great-grandparents, etc., in my past, and my children, grandchildren, great-grandchildren, etc. in my future.