Requested
The parring can go anyway though I personally have a crush on Ezra and Mira
A twin(Sakura) or fem Natu she/they are still fire dragon slayers but Sakura or Natsu have extra magic requip for the hunter gear thought that would have to come after she makes the gear or monster summoning only applies after taming it. I don't really think anything needs to change until the s class challenge besides some hunting/rescue missions. She could already be a s class who was nominated to stay at the guild she also specializes in hunting the beast from Monster Hunter her exeed/happy could double as her Palico. During the tenrou island arc Sakura/Natsu was kicked out of the guild(for the first 2 years she was constantly looking for everyone so she wasn't there alot maybe this caused resentment from the older generation) so here she is wondering around with out a purpose and one of the Monster Hunter guild masters find her and trains her for another 3 years to be a guild master for a Fiora guild branch(no one but the hunters know she is the master everyone thinks she is just the top hunter) this will give her 2 years to get up and running before everyone comes back.
Of course when the group get back and after they deal with the Ogre guild if twin route Natsu ask about her if femNatsu route it's Lucy when the group hears about her exile they are beyond furious after learning she "joined" a new guild they are obviously upset but are convinced that they can get her back(they still don't know it's been 7 years for comedic affect) cue meeting a not only older and more mature(battle hardened) Sakura/Natsu but she is also colder(sinical?) everyone but parring reaction😲😮😵 parring😍😳. For the tournament the Hunters guild could be a requested by the people guild participate and because of this there is a task to either hunt or tame one of the lesser beast from the game or they could be security. Or if you want to go a different route after 777 happens Sakura gets separated from Natsu or fem Natsu never makes it to Markov and a hunter finds her in a nest and takes her to the guild and she could meet her brother/parring on a mission or maybe a guild member exchange(kinda like a exchange student).