weak constraint or pointwise constraint

Hello,

I would like to have ur opinion for this situation:

I wish to constraint the (fluctuating) pressure to an average value of 20 [constraint expression: aveop1(p)-20] at the inlet boundary while pulsatile flow velocity is imposed at the inlet too.

I am not sure if weak constraint or pointwise constraint option is more suitable for this condition?
I read that weak constraint and pointwise constraint are similar but there is no Lagrange multipliers created in pointwise constraint. Anyone can please tell me what the importance of Lagrange multipliers in this case?

Thank you for your kindness.