This is truly a nightmare.
There are a few issues here and we need to look at them all.
The first is the selfish view.
Anything that upstages the bride (or groom to a lesser extent) is a nono. Even wearing a bright outfit with a BIG HAT in photos draws attention. Brides can be a real Brideasaurus and dress Bridesmaids in awful dresses so they look better, we all know the score here! Now imagine a person is at the wedding who draws eyes from EVERYONE there away from her all the time. Whispers pointing looking around. This will likely drive her crazy! If David Beckham and Posh were invited it would have the same reaction. No eyes on the bride!
The second issue is your expectations although it is common for single parents male or female to walk their child down the aisle if you are now another mum/auntie/ mommy dad/ or even just called by name as a friend of the family. No matter how this works out. It would causes some stares if a woman walked her down the Aisle. Especially one nobody recognises. Discretion would maybe be the better part of valor here and to discreetly sit at the back as that would be something and maybe leave before the couple leave? Only the ushers would need to be told this and it could go no further?
The next issue is parent (and children) being unable to cope with transition of a parent or child. For many they see this as some oddity and want to distance themselves from this inconvenience. To quote a often said comment the parent is partly to blame as they cooked the egg! So there is a lot of mental health going on here! Parents can feel guilty and ignorant as can children feel embarrassed (even with cis parents even dancing or telling a joke around their friends

) and ignorant of course as this is always somebody else's family problem. It has taken you all this time to come to terms with your lot it has taken them a very little time by comparison to adapt! So there is a pressure cooker issue where you are demanding them to adapt NOW TODAY! They simply may not be able to. You may have to be selfless for the good of everyone and accept that you need to step back for a while and in time the wounds may heal.
So this is just the tip of the iceberg, what they are all telling each other in private and the misinformation adds to this. There are no fast fixes.
In a nutshell
1. You somehow attend the wedding as a guest, well negotiated, leave early, do not attend the reception do not overdress and draw attention and keep it on the down low so only key people and ushers know who you are.
2. You back off and allow the repair of the family dynamic, allow them time to adjust (this may or may not take years! But in that time you can grow and create your new life).
3. Many people see transition as a very selfish thing to do! We all know that it is not your fault, you NEED to do this you need to be who you are. However, other people who do not understand these issues see this as just selfish. So it is a cruel blow to have to sometimes suffer a bit more and know you are being the bigger person by distancing yourself with love rather than hate. To back away and allow them space to live is probably the most gracious act of love you could possibly do. Letting go comes under the Kubler Ross stages of grief take a look at them and see if you can recognise them?
Visit our library here and have a read it may help
http://library.transgenderzone.com/?page_id=1986also see
http://library.transgenderzone.com/?page_id=498Hope this helps