You may already have, but could you define this word?
Theotokos literally, in Greek, means "God bearer" as in "one who carries" as in "to carry a child" as in "to be the mother of." The translation into "mother" is the problematic one for most and may be more of an English thing than Greek.
What it asserts is that Mary had in her womb a person who was God.
That's it. Mary carried God. She did not create God, she did not exist before God, she is not due an honor higher than God's. When God decided, actually when the Second Prrson of God decided, to become man he chose Mary to bring Him into the world. Mary gave birth to a person who is God.
The pronouncement of this doctrine arose from people denying that Jesus was God, or was eternally God (that Jesus "became" God at some point of his life, etc.) It is meant to show that at no time was there a person named Jesus who was only human. From His Conception He was a person both human and God.
SD
Then it would be better to show their error from the Biblical record, it is easy enough to do. Why invent a term that incorperates Mary in the mix. This just further confuses things to the "sheep". The cure is almost as bad as the disease. Step back and look at it as if you were hearing it for the first time" "Mary, the mother of God". If you are fair and honest you can see the problem with that statement. It implies that Jesus, who is God, did not exist before his human birth and that God himself sprang from Mary, rather than Mary being a created being, made by God. IOW, as with the other RC Mariology, it puts the emphasis in the wrong place.