Two figures are redrawn and merged into one. Are reproduction permissions required in this case? I have two questions regarding writing of survey papers

Firstly, if one of the technical papers reviewed has a number of figures. Take for example: Figure 4 is "Data model" and Figure 8 is "Mechanism structure". In the survey paper is it enough modification (for a waver of official permission) to merge these two into one figure and cite. Say, Figure X: Data model and Mechanism Structure adapted from [ref]? 

Secondly, in the case when author A proposes "Data model" and "mechanism structure" in paper [30] and [35] i.e four entirely different diagrams. Is it sufficient as modification (for a waver for official permission) if in a survey, all four combined in one figure. 

Thanks in advance
Combining other people's published figures to create a new figure does not allow you to waive requests for permission to reproduce a figure. Each individual component is someone else's intellectual property, and they have the right to be credited for the work. Note that many journals have simple mechanisms for requests to reproduce, and usually it's just a matter of asking for the necessary permission.

Simply redrawing someone else's figures for a part (a) and (b)-type figure does not spare you from requesting permissions. If you have completely redrawn and combined figures (for example, to illustrate how the two figures are more closely connected than in the originals), then you are creating a new intellectual contribution. You need to cite the original work that you've adapted, but you would not be reproducing the figures, and therefore would most likely not need to secure reproduction permissions.