Yet, we hear Christ saying earlier,
“For whoever does the will of my Father in heaven is my brother and sister and mother.”
Thus Mary is our mother too.
His mother and brothers were interrupting his teaching and so this was His response
Mark 3:31 And his mother and his bretheren came; and standing without, sent unto him, calling him. 32 And the multitude sat about him; and they say to him: Behold thy mother and thy brethren without seek for thee. 33 And answering them, he said: Who is my mother and my brethren? 34 And looking round about on them who sat about him, he saith: Behold my mother and my brethren. 35 For whosoever shall do the will of God, he is my brother, and my sister, and mother.
In other words we that come in faith as the Father wills are as dear to Him and as loved by His as His mother and family
This is not declaring her our mother
Jesus is using these terms to mean that those who do the will of God are members of his family. Its not interpretation to posit such a view,its a simple literary and contextual reading of the text.