As mentioned in section 9 of AN75779, you can connect multiple identical image sensors with FX3. If you are using 3 identical image sensors having pixel depth of 8 bits, then you can configure FX3 GPIF bus width as 24 bits and interface all the three sensors. Please note that this suggestion is based on the assumptions provided under Figure 51 of AN75779. Also, at the host side, you need to separate the interleaved images. For this, you need to develop your own custom host application.
Please go through section 9 of AN75779 to understand in detail about the implementation. Please let me know if you have any queries on this.