Examples of stacking circuit has been posted on the ADR5045 data sheet. Please refer to Figure.21.
Figure 21a shows three ADR5045 devices configured to give 15 V.
I use a 2.4V and 3.0V zener diode here, but it should work with your ICs as well:
The values of the resistors are not calculated; the circuit is just to show how it can be done.