Aiyo, congratulations! A slow-rising line on the T is actually quite common in twin pregnancies sebab hormone levels shoot up faster, so it's a good sign! A few of my mum friends who had twins mentioned their UPT lines came up super faint or slower at first, then got darker really quickly in the following days, so maybe do another test in a few days to see the progression, confirm je. The double pregnancy will show clearer on your first scan around 8-10 weeks anyway, so that's when you'll really know! Wishing you kembar jadi kenyataan, syabas on baby no. 4!