Parashat Lech Lecha - Freedom for all

In this Parasha we see Sara's attempt to ensure the continuity of the family she and Abraham created. Due to her infertility, Sara suggests that Hagar be the "surrogate mother" and that she will join in her motherhood. Sara's plan came to fruition but created a three-way tension between Hagar, Sara and Abraham. What were Sara's and Hagar's reactions? How is the value of freedom manifested in Abraham's house?