indexing I came across a child baptism with the name f the birth mother and also the adoppted parents
It helps if you can share the batch you are working on and the batch number.
The general rule if a child is adopted is to only list the adoptive parents.
And its possible you could use Or : example Mary Or Susan as mother's given name Smith Or Jones as mother's surname --in this case the maiden name would be <blank> --- Again the batch name & code are critical because different projects have different instructions
We would only use two or more names with 'or' if the names are different spellings or aliases of the same person. We never put the names of two different people in the same field that's meant for one person. If the specific project instructions don't address two sets of parents, the general rule has always been to index the adoptive parents, although in the past I've seen one project that specifically said to index the birth parents. So if the project instructions don't specify, follow the general rule. I wish I could give a link to the general indexing rule on this, but Family Search has made it much harder to find rules like this in the Indexing Helps.