Few things as an owner and sponsor of this community you have the ultimate rights to decide the next course of action for this forum. here are my few cents.
1. not clear on "joining forces" definition? you also mentioned about merger to strengthen this community. If its not merger then please clarify "joining forces" is it more than just collaboration? cross forum promotion or beyond that?
2. II forum is driven by members desire to have free and cost efficient trading solutions/education, unfortunately most come here to get free goodies , i am sure you would have realized that fact and hence desire to partner with multiple trading forums. with this regards since you mentioned of keeping those cracks programs/sharing of educational material under vault, how will this attract more users from other partnered forum as you may not be able to socialize that II offers these goodies?
3. agree on assessment that community needs cash to grow however another critical aspect is people participation, you can always think of monetarizing existing members with some perks and privileges.