What could be done if I have a little child who likes to block the place of prostration (sujud) when I offer my Prayer? I would move the child to another side; does this movement invalidate my prayer?
The Sunnah is to focus on your Prayer while observing khushu` (proper humility), whether it is an obligatory Prayer or supererogatory Prayer.
Responding to this question, Mufti Abdur-Rahman ibn Yusuf states: “It is allowed to move slightly during the prayer if necessary. As in your case, if your child comes in front of you during the prayer, you can take a quick step to the left or the right side and perform prostration and your prayer is still valid if Allah wills.”
Source: ZamZam Academy Channel on Youtube.