When splitting investment income do I calculate the split and enter on both returns or do I enter the total amount on my return and insert the appropriate % split?

You need to complete your slip how it appears on the paper. Usually, only one spouse need to complete the t5 slip . If you entered the % on this slip, the software will split this income on schedule 4(s) of each spouse.

Who is eligible to share investment income? Are seniors eligible or may they share pension income only?