There are not many interesting multiple stars in the Plejades as most of them are rather wide and do not really impress in the environmet of an open star cluster. I can not direct you to a site but give you a small list within or at least very near Pleijades: 19 Tau - wide triple star STF450 6.2" +7.3/9.1mag (secondary is according to my own observations rather fainter as advertised) S437 - wide double STT64 triple star 3.3/9.9" +6.8/10.1/10.5mag STF444 3.4" +6.9/10.1mag STF438 1.7" +9/10mag Wilfried
Actually that is STFA 7 or capital sigma, Roman numeral I, 7. That little error in Haas' book has been the source of much confusion over the years.
There are some other name errors in that book (among other types of misinformation, but overall a good reference), so if something doesn't seem quite right, check another source.