Best transfer for Europe Trip for Brother and his family?

[rdargar]

I am planning a Europe trip for my brother+2 (15-22 Days) in the month of June-July , which will be the best transfer partner for the same?

I hold M4B and can accumulate upto approx 2.7L points till May.
He holds an Atlas Card and can accumulate approx 20K miles (40K points) till May and already has 80K Accor points.

Suggestions needed for:

• Should he continue to transfer points in Accor only?
• Since the M4B is in my name which will be the best transfer partner which allows booking for family for a Europe Trip and provide good value.
• Any other suggestion/tip is most welcome.
• Should I book tickets now or wait 2-3 months?

We do not chase luxury but instead value . Economy class is absolutely fine , will be looking for Novotel,Swissotel in Accor.