Getting initials from multiple personnel over time

At work we have checklists that various steps get checked off and initialed by the person performing the work of each task, which may be done by an outside vendor or contractor at different times.  When all the tasks are done a supervising employee will print their name and sign the bottom.  The company wants to be able to fill these out and have the person performing a task to be able to initial on a computer or tablet that our employee will have. I can put in check boxes for the OK and the NA part and text fields for the any of the places to record info.  The issue I am having is figuring out how to implement the initials and signing.  I have made a few attempts and haven't found a good solution.  In general I have tried digital signatures and I have tried Fill and Sign and they both seem to be geared towards only one person using the computer to sign anything or to send the form to other people by email so they can open on their machine or device and use their saved signatures.  These solutions also seem to be more for the final signing of the entire document.  What the company would like is to be able to easily add initials at every task as we go, possibly saving and opening the document at a later time to record something in another task and initial, with finally printing the name and date when signing at the bottom.  Ideally, I would like to be able to tap or click a box and then the person signs their initials using the mouse or touchscreen, bonus points if you can sign once for multiple boxes.  Also, want to make sure the method used is as acceptable as handwritten initials, liability-wise.  The idea is to hopefully save time as there can sometimes be lots of forms and I dont want spend more time trying to initial the forms than it takes to do the work.  If anyone has some suggestions of how to accomplish this.

Below are some of my questions or issues with using Fill and sign or digital signature in more detail

Using Fill and Sign:

- You have to save a signature and initials and then drag and drop for each spot.  Would prefer a box to tap then just write initials

- Biggest issue, once the first person signs their initials and saves, the document can no longer be edited to record info or initial further steps.

Using Digital Signatures:

- Have to setup certificates, which is supposed to validate the persons identity somehow that I do not fully understand.  I can setup an "identitiy" for someone and then continue to use that, but having gone through the process I am not sure how it verifies the person  Mostly, I am trying to understand liability here should it come into question.

- Have to use a password each time, making it much more tedious and slower when signing off alot of tasks vs just doing it on paper.

- Changes made in other sections after initialing invalidates signature.

- I do like that once signed the corresponding check boxes and text boxes could be locked to read-only.

Any thoughts, suggestions or ideas?