You will have had an amazingly challenging time getting through a recurrence and I'm sorry your sister is also affected but congratulations on being here at BCNA. Lots of people have been so supportive here. There is also a private breast reconstruction group online which you can request membership here http://www.bcna.org.au/group/61026
I can feel a sense of urgency about making your reconstruction decision, but if you can take some deep breaths and spend some time thinking about what you will be most comfortable with. Is there a breast care nurse who knows women with reconstructions you can talk this over with?
With DIEP only, you only have one lot of tissue to work with for two breast reconstructions. With DIEP and implant perhaps it will be easier for a surgeon to achieve an aesthetic result with more to work with and less chance of tissue failing.
I am currently in preparation for reconstruction and have a tissue expander on one side. I'd like a DIEP to complete, but my surgeon is reluctant unless an ultrasound has found a decent supporting network of blood vessels that will maximise tissue survival, if I don't have that then he will do a modified TRAM.
I'm yet to start radiotherapy and later I'll be having genetic testing, so if anything turns up, I'll be in the same situation as you for reconstruction needing both sides done but with one side irradiated.
I see you have tagged your post as sad, so I'm sending you some virtual hugs and hope lots of people can tell you that you are not alone in having to deal with all the challenges.
Cheers, Meg xxx