When I clean and repair paintings, I "feed", the oils in the painting. This means, applying several coats of Copiav Balsam. This material adds the body and luster back into the oils. After curing, I repaint the repair areas as required. The only tricky part is to match colors and strokes of the original painter.
We are by no means an oil painting restorer, but we advise against using the Copailba balsam by itself as a restoration material. There are far better, and more archival products to be used.

Painting Materials: A Short Encyclopedia Gettens and Stout, Dover Publications, 1966 (1942). pg. 5 "The balsams most used in varnishing or as paint mediums are Venice turpentine, Strasbourg Turpentine, Canada Balsam, and Copaiba balsam. Balsams flow easily on a surface and give a lustrous, pleasing quality when first applied. Unless a harder resin is mixed with them, however, they deteriorate easily."

The Organic Chemistry of Museum Objects (2nd edition) Mills and White, Butterworth-Heinemann 1996 (1987), pg 105 "Their use in medicine is now discredited as is their one-time popularity with painting restorers who used them as an additive to the solvents used for removal of old varnish. Their effect was to act as a temporary varnish on the cleaned areas of the painting (since they do not evaporate completely), thus allowing the matte appearance inherent in the complete removal of the old varnish. Treatment with solutions of copaiba was one variation of the nineteenth and early twentieth century 'Pettenkofer process' for 'removing' old varnish for 'reforming' old varnish on paintings instead of removing it, and there is evidence of damage resulting from this."

We strongly suggest you abandon using this product for any oil restoration and instead use materials such as GOLDEN MSA Varnish and MSA Restoration Colors. These products can be removed for future restoration without removing the underlying original paints.

Additionally, most conservators use PVA glues for mounting and attaching materials as it also is very reversible.

Finally, the use of alcohol fumes to de-cup the paint chips is a practice that is frowned upon by conservators as it may allow the varnish to seep under the paint chips and then the entire painting is now pretty much removable with alcohol if more restoration is done later.

Like we said, we are not experts on this stuff, but if these paintings are worth the time to repair, they should be done as well as they can with materials that will not damage the artwork.