Vivica after joon

I’ve got joon at 3.70(and a rare yellow titan hopefully with my last darts) but after him. I’d like to use viv as my main healer. Currently I run triton, Melendor, Kiril, Joon, tiburtus(Scarlett) on defense all maxed with emblems. If I replace Mel with viv, should I put her center or corner? Assuming I use everyone but Mel, what’s a good defense setup? Eventually ill add Elena or khagan and other 5s as tc20 allows but for now what’s a good lineup with triton, Mel/viv, Kiril, Joon, tiburtus?
Also until she’s ready, is that the best order for current set? Triton, Mel, Kiril, Joon, tiburtus/Scarlett(depending on mood). I notice many put healers in corners but when I raid I kill the hitters leaving on healers which are quick kills.
Thanks for any suggestions. It gets expensive at this level to make errors so I’m trying to avoid them. Generally I am very high platinum 2300 and could push to diamond but would be raided back down. This setup has worked well and triton, Mel Kiril work great on offense with wu, gaderius, joon, tibs, li, gormek, Grimm, etc. Thanks again…