Create Random Points with a specific table

That's my question.

I have 3 tables in a Database: The first table is joined with another table (TABLE 3) where are stored 4 or more pairs of coordinates (so for one record of TABLE 1 there are more correspondences of record in TABLE 3). So, the TABLE 1 stores records that are represented like polygons in QGIS [For example ID 1(TABLE 1) = x1,y1; x2,y2; x3,y3; x4,y4 (TABLE 3)]. In the TABLE 2 there are records that are represented in QGIS like points linked with the TABLE 1 through an unique ID. I need the coordinates of the "TABLE 2" to calculated in a range between the coordinates of the "Table 3" (even randomly). The result in QGIS should be to random points inside a polygon.

I know that there is a command in fTools that randomly distributes the points, but the problem is that those random points that creates the program I do not know how to join them with the "Table 2". I hope I have expressed the problem correctly, because my English sucks :)