Sorry for your losses 
Here are some ideas:
Magnolia Maeve
Magnolia Lucy
Isadora Noelle (Noelle nod to Magnolia & Lucas)
Leonor(e) Maeve nn Leni
Camellia Maeve (Camellia mix of Magnolia & Elliot)
Delphine Maeve
Meadow Lucy-Jean
Elowen Lucy-Jean nn Winne/Lola*
Lucien Augustus (Lucien a mix of Lucas and Jean)
Lachlan Augustus (as above)
Julian Augustus (as above, too close to Juniper?)
Magnus Theodore (Magnus is also Magnolia plus Lucas)
Cyrus Jean-Luc**
Felix Jean-Luc (Felix a good name after loss)
Edmund Jean-Luc or Edmund Augustus nn Eddy or Teddy
Rafferty Augustus
*I personally don’t like Ellie at all so any possibly Ellie nickname name is a no for me.
**Would have these as a middle not first name - think could be slightly onerous to have the names of siblings who have passed as your first name. It’s a lot to explain and also might feel like he has to live for them etc (subconsciously). I think middle spot much better, obv take or leave my thoughts…