PDEs expressed in Weak Form Coupled to ODEs

Hello,

I am currently using COMSOL 4.3a.

I am solving a problem constituted by a set of coupled PDEs (depending on time and space), defined in a domain.
To solve this, I used the Weak Form.

In addition, coupled to the PDEs, I have 2 ODEs (only depending on time). I implemented the ODEs, in the same fashion of the PDEs, using the Weak Form.

However, I wonder if there is any alternative way to include the ODEs different from what I did. For instance, is there the possibility of introducing the ODEs as expressions that apply to the entire domain.

Has anybody an idea if this is possible and how?
thanks