Have you attempted to use the forms found in the Annex of D1.1? They include a blank form and then a form that is filled in to show what information is placed where.
You can use the same format for D15.1 if I remember correctly.
It is best if one can fill in the forms and understands what goes where if they are responsible for welding operations. It is not that difficult to follow the format included in D1.1. However, I generate the forms using MS Word or if one prefers, use an MS Excel spreadsheet format. I like the word processor for the WPS because it is easier to expand or contract the form. For instance, I might expand the form to accommodate information about cleaning. When welding titanium I expand the details about precleaning, interpass cleaning, and post welding cleaning. When addressing filler metals I might expand the form when I want the welder to use a specific brand name available from a specific manufacturer because I need extra manganese to counter the sulfur content of the casting being repaired. Having your own forms gives you flexibility you will not find with a "canned" program.
The other thing to keep in mind, the "canned" programs are fine for general, run of the mill type work, but they are not so adept at handling unusual combinations of base metal or welding standards that are not main stream. D15.1 could be considered to fit the later category because it has a limited customer base, so it isn't going to sell as well as a program intended to satisfy D1.1. That being the case, it is difficult to make the preformatted forms "fit" the specific welding standard you may be working with. Why? Because, the essential and nonessential variables change from one welding standard to another.
Writing a good WPS can be a challenge, but the effort is worthwhile. Just remember who your audience is. You are writing the WPS for a welder. The information presented should be in a format the welder can use. Too many WPSs are written by engineers for other engineers. The information provided is of little use to the welder. For example, few welders will find an entry on the WPS that states "All Group 1 base metals as found in Table 3.1 of AWS D1.1" very informative or useful. It is better to list the applicable base metal specifications and grades, if not on the WPS, they can be listed in an Annex attached to the WPS. If the WPS is for a specific part that is composed of one, two, or three different base metals, it is easy enough to list those base metal specifications on the WPS.
The same is true of the joint details. The WPS can include the specific joint details used if there are only one, two, or several typical joints. If the nature of the work and the WPS is used for a variety of parts, the joint details can be detailed in an Annex and the WPS would simply reference the Annex. That works very well when there is coordination between the engineering department and the production department. If the system is working, the joint detail is referenced in the tail of the welding symbol. The welder simply looks up the detail referenced by the welding symbol in the Annex. Everything the welder needs to properly fit the joint is easily located. Likewise, all the information needed by the inspector, i.e., the min./max. groove angle, min./max. root opening, etc. is readily available when performing the fit up inspection.
Look at that, we started the conversation talking about WPSs and now we are talking about a coordinated manufacturing system.
Best regards - Al