In our field (biomedical research), it is increasingly common to have 2 or more first authors who are recognized for equal contribution. The designation is captured in PubMedCentral, though I can’t tell if PubMed also includes it. For in-text citations that use a style “author, et al. year” is there a way to include all the first authors? Otherwise, we are ignoring the other equal authors.
So far, I haven’t seen any journal instructions on how to handle this. Bibliographies are designed to find articles, and not really to assign author contributions. Hence senior authors at the end - aren’t recognized in most bibliography instructions, especially those that shorten the number of authors to et al if over 3 or 5, etc. You could try to keep the asterisk and another field to include text **these authors contributed equally to this work, after the author field in your bibliographic style, but I am not sure it will make it thru the editorial review and published that way. There are many discussions about how to measure “equally credited authors” (both first and senior) or designate co-first authorship in CVs. None seem to address this in the in-text citations, nor bibliographic recognition.