I am just gathering all I can on information regarding a TOLAC and VBAC carrying twins for a second pregnancy.
As it turns out, we have some data on VBACs with twins. Ford et al. (2006) looked at 1850 planned VBACs with twins. The scar rupture rate was 1 per 100 overall. Keep in mind as well that having the scar open in almost all cases means nothing more than the need for repeat cesarean. A bad outcome for babies or mother after scar rupture is exceedingly rare. The risk of death secondary to scar rupture during VBAC labor in a large U.S. study was 1 per 10,000, a risk in the same ballpark with the risk of maternal death in that same population of 3 per 10,000 after elective repeat cesarean (Landon 2004; Spong 2007). As you can see, elective repeat c/sec isn’t harmless. Another study (Miller 1996) compared 92 twin planned VBACs with 118 planned c/sec and reported no major complications in the VBAC group, but a maternal death (pulmonary embolism) in the planned c/sec group and two hysterectomies. Your problem, though, will be in finding someone to attend you. Finding someone who does VBACs is hard, finding someone who does twin vaginal births is hard too, which means finding someone who will do a twin VBAC is almost sure to be really, really difficult. I wish I knew more that could help you with that piece.