Meteor react design - nested component: function call

I’m currently facing a problem with Meteor and React, where i know some partly solutions but they don’t work and imo none of them is pointing in the true direction.

The situation:

All is about an fitness app: I have a structure that represents exercises for customers, while each exercise can have a defined number of sets (a set is how often a exercise should be done). Each set has some properties (all the user can manipulate within the font-end).

Now i have the following component structure with some map-functions (state properties are in {}):

Training {customers,exercises,datetime,otherinfos}
    - Overview {customers,exercises}
         - Exercise {exercise,customers}
              - Customer {exercise,customer}
                    Set {exercise, customer, set, valuesofset}

From a UI-perspective (react) this all works without problems.

Now the idea is to have a button “Save” within the Training component. When the button is pressed, I want to save the state of all Set-Components in a “sets” collection (if it has other values than the default placeholder ones) and at the same time save the Training-Component in a “trainings” collection. But the training should also include information about what Sets are integrated (so at least the Set._id should be in the Training-Component state at time of Saving.

Here now my ideas so far:

Create refs from Training all the way down to all Sets and then, when pressing “Save” iterate over all refs and call a “Mongo.insert” from all Sets. Here i have the problem that i cannot return the inserted _id. Of course i could call a different function in each Component from Set all the way back to Training, but imo this is an overflow.

Try to manage the state of all sets within the Training state by calling a nested function. As i have onChangeHandler on the Inputs, this would always call a method in Training and check which one of the Sets was changed and then changes it. I have tried it this way, but it led to a very bad performance.

Create a temp-ID for Training, forward it to to the Sets (using the componentWillReceiveProps method) and when in Set, insert the Set in the database with the temp-ID. Then receive all Sets with temp-ID and use it to add the Training in the database. --> imo very complicated and I don’t really want to do a database call if it is not necessary.

So currently i don’t know how to solve this problem. The reason i try to separate “sets” and “trainings” is given through the fact, that later on i would like to give information about the last Set right next to the new empty Set whenever one is on the database. Any tips are welcome!