To clarify, You want to take your 3 children plus yourself to Orlando? Domestic UA redemptions for that flight can be 25k points round trip per person, if saver availability is open, or 50k points rt pp for standard award availability. Finding 4 tickets can be tricky too. So you're looking at 100k-200k in redemption miles needed for your flights.

Your 5k UA points sadly won't do much unless you were to add a large credit card signup bonus such as from the Chase Sapphire and/or UA cards. It'd doable if you can get the approvals & accomplish the minimum spending.

The Venture Card can help reduce your costs as it's based on purchasing the tickets via the Capital One Travel Portal and then applying a fixed rate reduction in cost per point. At this point it might be easiest for you to focus on this to reduce your costs.