Tharpanam is usually performed for two groups of ancestors. My doubt is related to when a sumangali attains AcAryan Tiruvadi – in such case, her son performs pratyAptika shrAddham only and does not perform tharpanam on other occasions amavasai, etc. as the husband/father is still alive. The husband/father performs tharpanam only for his pitru and mAtru vargams (groups). The departed soul of the sumangali, though it has joined her varga during sabindikarana, is that soul left out while performing tharpana? What is its situation until the time the husband attains the ParamaPadam? Pray to the elders to clarify this.

Scriptures have ordained the types of food that need to be offered to the devas and pitrus and the times when they should be offered. It is enough that we do as ordained and ensure no shortcomings occur.
Notes:
As per Sri Vaishnava tradition, if a sumangali passes away after prapatti, she will attain salvation, after which there is no hunger or thirst. That soul is not sustained by the performance of tharpanam. We perform tharpanam to please the Paramatma, who is an antaryAmi in that soul.
The performance of tharpanam does not satisfy a father or grandfather who is in the forms of pitru devatas, but it satisfies the antaryAmi Bhagavan. That is the reason when we begin tharpanam, we say ‘Bhagavat preethyartham’.