I've found that grafting fig scions onto another fig plant is more challenging than grafting cuttings from other fruits
like apples onto an apple root stock or an apple mother tree. The most exotic thing I've seen
was a tomato branch grafted onto a potato plant! A straw was used to hold the connection steady.

Has anyone tried to graft any fig trees while the sap is flowing and the tree is out of dormancy and succeeded?
I tried it twice and failed both times.

@Sas:

Yes... in tropical environment we always do like that...

Thank You

Get comfortable; I'm gonna take you down a little trip into Bizarro Land.  In Sacramento, my son & I went to do a little service to an elderly couple and do some top work on their stone fruit and their apples.  He took us aside and told us that he had a fig branch coming out of his orange tree.  It was there when they moved into this house a few years before.  We explained that things like that aren't possible because of the things that we've already discussed in this forum.  He took us over to look at it.  All three of us were on our hands and knees examining it for a half hour, and we concluded, YES, he had a fig branch coming out of his orange tree!  Can anyone explain that?  It was down not too far above the soil.  The "fig" branch never produced fruit as far as I know.  It was a big, healthy, and mature branch.  Three of us saw it, touched it, laid sideways on the ground to get up close, and we all agree that it was real.  There's plenty of evidence that it didn't happen.  But can anyone argue that my conclusion is correct?  Remember, it didn't bear fruit, so I'm not advocating that it's worthwhile, just possible.  

I once visited an overgrown garden where many of the cordoned apple trees had enveloped and grown around the metal fence they were originally trained on to. I have also seen different species of trees growing around and through each other but they still weren't joined directly to each other. Could it have been something similar?

I wonder how far across a phylogenetic tree you can take interstem grafting.  With enough well chosen interstems could you get F.carica to take on a mulberry?  Just curious what would be required....no plans to experiment on my part.