Software for merging two wav files

Required technical expert to design a functionality,

We are an audio production house based in India.

We have composed few songs that we plan to release in a couple of days.

The songs have been composed as dedications for your girl / boy friend or wife / husband.

The USP of our service is personalization.

To simplify, the user of our service can add his / her own personalized message for the person he / she wants to dedicate the song to.

The songs have been composed in way that there is scope to add a personalized messages “TWICE” in every song depending on the musical composition.

The points at which the personalized message can be added in a particular song are different as it depends on the musical composition.

To simplify, say in song A the personalized message can be added at 5.2 seconds and 1.55 minutes into the song.

At the same time in song B the personalized message can be added at 8.5 seconds and 2.34 minutes into the song.

We need a functionality to be designed in ………….which will help us to mix a desired personalized message with any of the songs.

Point to remember we have more than 10,000 personalized messages which have to be mixed with every song and the duration of these personalized message is not same.

The desired functionality should be able;

1. to mix these personalized messages at designated points at one go (in a batch not individually).
2. save it as an individual track / song.

We are currently working on Adobe Audition and Gold Wave and are able to make the desired changes

but for that we need to edit and make a separate voice file for the personalized message and

then we are able to mix it in the batch. Now we want to save the editing time and hence we need an application

which will dynamically add the personalized message where ever we want to add it.